1
Q
What is pair production?
A
A phenomenon where a high-energy photon creates an electron-positron pair.
2
Q
What particles are produced in pair production?
A
An electron and a positron.
3
Q
What is the minimum photon energy required for pair production?
A
1.02 MeV.
4
Q
What is the rest mass energy of an electron?
A
0.511 MeV.
5
Q
What is the rest mass energy of a positron?
A
0.511 MeV.
6
Q
Why is 1.02 MeV the threshold energy for pair production?
A
Because it equals 2 × 0.511 MeV (electron and positron mass energy).
7
Q
Can pair production happen in free space?
A
No, it requires a nearby nucleus or particle to conserve momentum.
8
Q
What law prevents pair production in empty space?
A
Conservation of momentum.
9
Q
What is the role of the nucleus in pair production?
A
It absorbs recoil momentum and ensures momentum conservation.
10
Q
What happens to excess energy if the photon energy is more than 1.02 MeV?
A
It becomes kinetic energy of the electron and positron.
11
Q
What happens to the positron after creation?
A
It eventually annihilates with an electron.
12
Q
What is emitted when a positron annihilates with an electron?
A
Two gamma photons.
13
Q
What is the energy of each photon in electron-positron annihilation?
A
0.511 MeV.
14
Q
What direction are the two annihilation photons emitted in?
A
In opposite directions (to conserve momentum).
15
Q
What is the name of the reverse of pair production?
A
Annihilation.
16
Q
Which fundamental force is involved in pair production?
A
Electromagnetic force.
17
Q
Is pair production an example of matter creation?
A
Yes.
18
Q
What kind of photon initiates pair production?
A
A high-energy gamma ray.
19
Q
What law ensures total energy before and after pair production is the same?
A
Law of conservation of energy.
20
Q
What is required for both energy and momentum conservation in pair production?
A
A nearby nucleus or particle.
21
Q
Can X-rays cause pair production?
A
Only if their energy exceeds 1.02 MeV.
22
Q
What’s the symbol for a positron?
A
e⁺
23
Q
What’s the symbol for an electron?
A
e⁻
24
Q
Is positron a matter or antimatter particle?
A
Antimatter.
25
What happens if pair production occurs near an electron instead of a nucleus?
It’s called triplet production.
26
What is triplet production?
Pair production where the third body is an electron, not a nucleus.
27
What is required for triplet production?
Photon energy above 2.04 MeV.
28
What does pair production demonstrate about energy and mass?
Mass can be created from energy.
29
Who proposed the mass-energy equivalence that supports pair production?
Albert Einstein.
30
What equation supports pair production theoretically?
E = mc²
31
Is kinetic energy produced in threshold pair production?
No, only rest mass is created at the threshold.
32
What field of physics studies pair production?
Modern physics or quantum electrodynamics.
33
Is pair production reversible?
Yes, through annihilation.
34
What is the conservation rule applied to charge in pair production?
Total charge before and after remains zero.
35
Why are two photons created in annihilation?
To conserve both energy and momentum.
36
What is the lifetime of a positron before annihilation?
Very short, typically microseconds or less.
37
Where is pair production observed in real life?
Particle accelerators and cosmic ray interactions.
38
What happens in PET scans related to pair production?
Annihilation of positrons emits gamma rays for imaging.
39
What is PET in medical imaging?
Positron Emission Tomography.
40
Which conservation laws are satisfied in pair production?
Energy, momentum, charge, and lepton number.
41
How many leptons are present after pair production?
Two (electron and positron).
42
Is lepton number conserved in pair production?
Yes, net lepton number remains zero.
43
Can pair production happen with muons instead of electrons?
Yes, but requires higher photon energy.
44
What is the threshold energy for muon pair production?
About 211 MeV (2 × 105.7 MeV).
45
What kind of spectrum can include photons capable of pair production?
Gamma-ray spectrum.
46
What stops pair production from happening at low photon energies?
Insufficient energy to create rest mass.
47
What is antimatter equivalent of an electron?
Positron.
48
What is pair annihilation?
Process where an electron and positron destroy each other, releasing energy.
49
What is a gamma photon?
A high-energy photon capable of initiating pair production.
50
Is pair production direct evidence of E=mc²?
Yes, it demonstrates energy converting into mass.
51
What is the Compton Effect?
It is the increase in wavelength of X-rays or gamma rays when they are scattered by electrons, proving that light behaves like a particle (photon).
52
What is the formula for Compton shift?
Delta lambda = (h / m_e × c) × (1 - cos theta)
53
Which experiment proves the particle nature of light?
Compton Effect proves that light has particle properties.
54
What is the Compton shift at 0° scattering angle?
Zero. There is no change in wavelength.
55
What is the maximum Compton shift angle and its value?
At 180°, the shift is maximum: 0.00486 nm.
56
What particle does the photon collide with in Compton Effect?
A free or loosely bound electron.
57
Which laws are obeyed during Compton scattering?
Conservation of energy, charge, linear momentum, angular momentum, and lepton.
58
What are the SI units of Planck’s constant?
Joule-second (J·s)
59
What is the speed of light in a vacuum?
3.0 × 10⁸ meters per second (m/s)
60
What is the formula for energy of a photon?
E = h × frequency
61
How is frequency related to energy?
Directly. Higher frequency means higher energy.
62
What is the relation between frequency and wavelength?
Inversely proportional. As frequency increases, wavelength decreases.
63
What does ‘h’ represent in modern physics?
Planck’s constant
64
Define a photon.
A photon is a particle of light with energy but no mass or charge.
65
What happens if the frequency is below threshold frequency?
No photoelectrons are emitted, no matter how intense the light is.
66
What is the work function of a metal?
The minimum energy needed to eject an electron from its surface.
67
Write Einstein’s photoelectric equation.
K.E. max = h × frequency − work function
68
What happens if we increase light intensity above the threshold?
More photoelectrons are emitted.
69
What happens when we increase frequency above threshold?
Photoelectrons become more energetic (higher kinetic energy).
70
What is photoelectric current?
Current formed due to the flow of emitted photoelectrons.
71
What is stopping potential in the photoelectric effect?
The minimum negative voltage needed to stop the fastest photoelectrons.
72
What is the kinetic energy of photoelectrons at stopping potential?
Zero. All kinetic energy is used against the voltage.
73
What is the photon energy formula using wavelength?
E = (h × c) / wavelength
74
In what units is work function usually expressed?
Electron-volts (eV)
75
How much is 1 electron-volt in joules?
1 eV = 1.6 × 10⁻¹⁹ joules
76
Can photoelectric effect happen with red light?
Only if its frequency is above the threshold frequency of the material.
77
Is photoemission instantaneous or delayed?
Instantaneous. Electrons are emitted as soon as photon energy is absorbed.
78
Why is a clean metal surface used in the photoelectric experiment?
To allow free electrons to escape easily.
79
Does intensity affect kinetic energy of photoelectrons?
No. Kinetic energy depends on frequency, not intensity.
80
How is Compton Effect different from Photoelectric Effect?
Compton: photon scatters off electron. Photoelectric: photon ejects an electron.
81
Zinc has a work function of 4.3 eV. Find the minimum frequency required.
Threshold frequency = 4.3 / (6.63 × 10⁻³⁴) ≈ 6.49 × 10¹⁴ Hz
82
What is the Compton wavelength of an electron?
0.00243 nm
83
What is the slope of the kinetic energy vs frequency graph?
Planck’s constant (h)
84
What physical quantity is measured in Compton’s experiment?
The change in wavelength of scattered X-rays.
85
What dual nature of light is proven by modern physics?
Light behaves as both a wave and a particle.
86
If no photoelectrons are emitted, what could be the reason?
The light’s frequency is below threshold.
87
What is the energy of a UV photon of 300 nm?
≈ 4.14 eV
88
Who gave the correct explanation of the photoelectric effect?
Albert Einstein (1905)
89
Who won the Nobel Prize for explaining the photoelectric effect?
Albert Einstein in 1921
90
What is the formula for stopping potential?
e × V = h × frequency − work function
91
Will photoemission occur with low frequency and high intensity light?
No, if frequency is below threshold.
92
What is a common use of the photoelectric effect in devices?
Photocells in automatic doors, calculators, light sensors.
93
Which light has the shortest wavelength – red or violet?
Violet
94
Is infrared light high or low energy compared to visible light?
Low energy
95
Which metals are easily photoemissive?
Alkali metals like cesium, potassium, sodium.
96
What does light intensity represent in photon terms?
Number of photons striking per second.
97
Why does photon have zero rest mass?
It always moves at the speed of light.
98
How are stopping potential and K.E. of photoelectrons related?
Stopping potential = K.E. max / electron charge
99
The photoelectric effect works only with what kind of light?
Light of frequency greater than threshold frequency.
100
Is photoemission delayed over time or immediate?
Immediate. One photon ejects one electron instantly.
101
What is the formula of Stefan–Boltzmann Law?
Power = sigma × Area × Temperature⁴
## Footnote
(Sigma = 5.67 × 10⁻⁸ W/m²·K⁴)
102
What are the SI units of Stefan’s constant?
Watts per square meter per Kelvin⁴ (W/m²·K⁴)
103
What is the formula for Wien’s Displacement Law?
Lambda max × Temperature = b
## Footnote
(b = 2.898 × 10⁻³ m·K)
104
Why did Rayleigh–Jeans law fail?
It predicted infinite energy at short wavelengths (ultraviolet catastrophe).
105
What happens to radiation if temperature doubles?
Radiation increases 16 times (2⁴ = 16)
106
If temperature increases, what happens to lambda max?
Lambda max decreases (inverse relation)
107
Peak wavelength of Sun is 500 nm. What’s the temperature?
T ≈ 5800 K
108
What is power radiated by a perfect black body?
P = sigma × Area × T⁴
109
What is Stefan’s Law for non-black bodies?
P = e × sigma × A × T⁴
## Footnote
(e = emissivity)
110
Total energy radiated is proportional to what power of temperature?
Fourth power (T⁴)
111
When is Rayleigh–Jeans Law accurate?
At long wavelengths and low frequencies
112
What is the basic form of Einstein’s photoelectric equation?
Kinetic Energy = Photon Energy − Work Function
113
How to find work function from threshold frequency?
Work function = Planck’s constant × threshold frequency
114
What is frequency if photon energy is known?
Frequency = Energy / Planck’s constant
115
How to find wavelength from energy?
Lambda = (Planck’s constant × speed of light) / energy
116
In what units is kinetic energy commonly given?
Electron-volts (eV)
117
What are standard units of work function?
Electron-volts (eV)
118
What is the 1240 rule in light problems?
E (eV) = 1240 / wavelength (nm)
119
How is kinetic energy related to stopping potential?
KE = charge × stopping potential
120
What is the formula for Compton shift?
Delta lambda = (h / m × c) × (1 − cos theta)
121
What is the Compton constant for electron?
0.00243 nm
122
What is Compton shift at 180 degrees?
Maximum: 0.00486 nm
123
What is Compton shift at 0 degrees?
Zero
124
What is Compton shift at 90°?
0.00243 nm
125
How to convert nanometers to meters?
Multiply by 10⁻⁹
126
What is the kinetic energy at threshold frequency?
Zero
127
What is Planck’s constant in eV·s?
4.14 × 10⁻¹⁵ eV·s
128
What is the speed of light used in calculations?
3 × 10⁸ m/s
129
How to find frequency if wavelength is given?
Frequency = speed of light / wavelength
130
What are the two common units of photon energy?
Joules (J) and electron-volts (eV)
131
Photon energy = 5 eV, work function = 2 eV. Find KE.
KE = 5 − 2 = 3 eV
132
Photon energy = 6 eV, KE = 2 eV. Find work function.
Work function = 6 − 2 = 4 eV
133
Work function = 3 eV. Find threshold frequency.
f = 3 / (4.14 × 10⁻¹⁵) ≈ 7.25 × 10¹⁴ Hz
134
What is the slope of KE vs frequency graph?
Planck’s constant (h)
135
What are the units of Wien’s constant b?
meter·Kelvin (m·K)
136
What is the average peak sensitivity of the human eye?
Around 550 nm (green)
137
A = 2 m², T = 500 K. Find radiated power.
P ≈ 1417 watts
138
What color does a blackbody emit at high temperature?
It shifts from red to blue as temperature increases.
139
What is the SI unit of frequency?
Hertz (Hz)
140
How to convert Joules to eV?
Divide by 1.6 × 10⁻¹⁹
141
Power ∝ T⁴ means if T triples, power increases by?
3⁴ = 81 times
142
Energy = 5 eV. What’s the frequency?
f = 5 / (4.14 × 10⁻¹⁵) ≈ 1.21 × 10¹⁵ Hz
143
Define blackbody radiation.
Radiation from an object that absorbs and emits all wavelengths perfectly.
144
Who solved the ultraviolet catastrophe?
Max Planck by quantizing energy
145
What is the pressure of radiation from a blackbody?
P = U / 3 (U = energy density)
146
Common units of wavelength in physics?
Meters, nanometers, angstroms
147
How does Wien’s Law help astronomers?
It helps estimate the temperature of stars from their color.
148
How many electrons can a single photon eject?
One photon can eject at most one electron.
149
Why is energy needed to emit electrons from metal?
Because electrons are bound by work function energy inside the metal.
150
What is the minimum energy required for pair production?
1.022 MeV
151
What particles are produced in pair production?
An electron and a positron
152
Why is the energy threshold for pair production 1.022 MeV?
Because 0.511 MeV is the rest mass energy of each particle
153
Can pair production occur in empty space?
No
154
What role does the nucleus play in pair production?
It absorbs excess momentum to conserve momentum
155
Does the nucleus lose energy in pair production?
No
156
Is the nucleus altered during pair production?
No
157
What happens to the energy of the photon in pair production?
It is converted into mass and kinetic energy of the particles
158
What is positron annihilation?
The process where a positron meets an electron and they produce two gamma photons
159
What is the energy of each photon in annihilation?
0.511 MeV
160
What is triplet production?
Pair production occurring near an electron instead of a nucleus
161
What particles result from triplet production?
Electron
162
Can pair production happen with visible light?
No
163
What does the extra energy in pair production become?
Kinetic energy of the electron and positron
164
Why does the photon disappear in pair production?
Its energy is fully used to create the mass and motion of particles
165
What is the reverse of pair production?
Annihilation of matter and antimatter
166
Why is momentum conservation important in pair production?
Because photons have momentum and final particles must balance it
167
What ensures energy conservation in pair production?
The total energy before and after remains the same
168
Why can’t a photon produce just one electron?
Charge conservation would be violated
169
Is pair production possible in vacuum?
No
170
What is the rest mass energy of an electron?
0.511 MeV
171
What is the charge of a positron?
1
172
Is the positron a stable particle?
No
173
What particles are involved in Compton scattering?
Photon and electron
174
What happens to the photon in Compton effect?
It is scattered at an angle with reduced energy
175
What happens to the electron in Compton effect?
It recoils and gains kinetic energy
176
What ensures energy conservation in Compton effect?
The photon’s energy splits between the scattered photon and electron
177
What ensures momentum conservation in Compton effect?
The electron recoils in the opposite direction of photon scattering
178
What is the Compton wavelength shift equation?
Δλ = h/mc × (1 - cosθ)
179
What is the Compton wavelength shift dependent on?
The angle of photon scattering
180
What type of photon is typically used in Compton effect?
X-rays or gamma rays
181
Does Compton effect occur with visible light?
No
182
Why does the photon lose energy in Compton scattering?
Some energy is transferred to the electron
183
What is the Compton edge?
The maximum energy transferred to the electron
184
What happens to the recoiled electron?
It moves away with kinetic energy and may ionize other atoms
185
Does the electron return to the atom in Compton effect?
No
186
Is the nucleus involved in Compton effect?
No
187
Can the Compton effect ionize atoms?
Yes
188
Is energy conserved in Compton effect?
Yes
189
Is momentum conserved in Compton effect?
Yes
190
What is the formula for photon energy?
E = hf
191
What is the formula for photon momentum?
p = h/λ
192
What is the speed of the photon before interaction?
Speed of light (c)
193
What determines the direction of scattered photon?
Angle of impact and conservation laws
194
Why is Compton effect evidence for particle nature of light?
Because it shows momentum transfer like in particle collisions
195
Does the Compton effect violate wave theory?
Yes
196
What is elastic scattering?
Scattering where total kinetic energy is conserved
197
Is Compton scattering elastic?
No
198
What is meant by recoil?
Backward motion of a particle after impact
199
What is the recoil angle?
The angle at which the electron is scattered
200
What is the maximum kinetic energy in Compton effect?
When photon is backscattered (θ = 180°)
201
What is the minimum change in wavelength in Compton effect?
When θ = 0° (no scattering)
202
What happens when θ = 180° in Compton effect?
Maximum wavelength shift and energy loss by photon
203
What is meant by pair?
A particle and its antiparticle
204
What is the mass of positron?
Same as electron (9.1 × 10⁻³¹ kg)
205
What is photon annihilation?
Destruction of photon when its energy converts into matter
206
How many photons are produced in annihilation?
Two
207
Why are two photons produced in annihilation?
To conserve momentum
208
Why can’t pair production create only one particle?
That would violate conservation of charge
209
Where does pair production usually occur?
Near heavy nuclei
210
What is pair annihilation?
When electron and positron meet and convert into gamma rays
211
What is required for annihilation to happen?
Electron and positron must meet
212
What happens to the energy in annihilation?
Converted into two photons of 0.511 MeV each
213
What is the outcome of matter-antimatter collision?
Pure energy (gamma photons)
214
Is pair production reversible?
Yes
215
What kind of reaction is pair production?
Energy to mass conversion
216
What kind of reaction is annihilation?
Mass to energy conversion
217
What happens if photon energy is more than 1.022 MeV?
Extra energy goes into kinetic energy of particles
218
What kind of photon energy is best for pair production?
Gamma rays with energy ≥ 1.022 MeV
219
Can Compton effect happen in solids?
Yes
220
Can pair production happen in solids?
Yes
221
What is conserved in pair production?
Energy
222
What is conserved in Compton effect?
Energy and momentum
223
Which effect supports wave nature of light?
Interference
224
Which effect supports particle nature of light?
Photoelectric effect
225
Why does Compton effect need free or loosely bound electrons?
Tightly bound electrons distort conservation equations
226
What is the difference between Compton effect and photoelectric effect?
Compton gives scattered photon
227
Why is pair production not a classical effect?
It involves quantum transformation of energy into mass
228
Which quantum equation relates energy and mass?
E = mc²
229
Which quantum equation relates energy and frequency?
E = hf
230
Which equation relates momentum and wavelength?
p = h/λ
231
What does the h represent in quantum physics?
Planck’s constant
232
Is energy quantized in Compton effect?
Yes
233
Is energy quantized in pair production?
Yes
234
Why is Compton shift measurable?
Because X-ray and gamma ray wavelengths are small enough to detect changes
235
Can Compton effect happen with bound electrons?
Yes
236
Can pair production occur with UV light?
No
237
Is the recoiled electron in Compton effect the same as in pair production?
No
238
What is the direction of the positron in pair production?
It moves in a random direction
239
What happens to the positron after creation?
It slows down and annihilates with an electron
240
Does pair production happen in stars?
Yes
241
Is antimatter real?
Yes
242
What is PET scan based on?
Positron emission and annihilation gamma rays
243
What is the lifetime of a positron?
A few nanoseconds before it annihilates
244
What is a photon?
A quantum of electromagnetic energy
245
What is antimatter?
Matter with opposite charge and quantum numbers
246
Which laws govern Compton and pair production?
Conservation of energy and momentum
247
Can pair production happen in medical imaging?
Yes
248
Can Compton effect degrade image quality?
Yes
249
What is the outcome of the photoelectric effect?
Ejection of an electron from the metal surface
250
What is the outcome of the Compton effect?
Scattered photon and recoiled electron
251
What is the outcome of pair production?
Creation of an electron and positron
252
What is the outcome of pair annihilation?
Two gamma-ray photons are produced
253
Does the photon survive in the photoelectric effect?
No
254
Does the photon survive in the Compton effect?
Yes
255
Does the photon survive in pair production?
No
256
Does any photon exist before pair annihilation?
No
257
Is mass created in pair production?
Yes
258
Is mass destroyed in pair annihilation?
Yes
259
Are new particles formed in photoelectric effect?
No
260
Are new particles formed in Compton effect?
No
261
Are new particles formed in pair production?
Yes
262
Are new particles formed in pair annihilation?
Yes
263
Is energy converted into mass in photoelectric effect?
No
264
Is energy converted into mass in Compton effect?
No
265
Is energy converted into mass in pair production?
Yes
266
Is mass converted into energy in pair annihilation?
Yes
267
What happens to the photon in the photoelectric effect?
It is fully absorbed by the electron
268
What happens to the photon in Compton effect?
It is scattered with lower energy
269
What happens to the photon in pair production?
It disappears
270
What happens to particles in pair annihilation?
They vanish and convert into photons
271
Does the photoelectric effect involve antimatter?
No
272
Does the Compton effect involve antimatter?
No
273
Does pair production involve antimatter?
Yes
274
Does pair annihilation involve antimatter?
Yes
275
Is momentum conserved in photoelectric effect?
Yes
276
Is momentum conserved in Compton effect?
Yes
277
Is momentum conserved in pair production?
Yes
278
Is momentum conserved in pair annihilation?
Yes
279
What is released in photoelectric effect?
Photoelectron
280
What is released in Compton effect?
Recoil electron and scattered photon
281
What is released in pair production?
Electron and positron
282
What is released in pair annihilation?
Two gamma photons
283
Can photoelectric effect happen with visible light?
Yes
284
Can Compton effect happen with visible light?
No
285
Can pair production happen with visible light?
No
286
Can pair annihilation happen with visible light?
No
287
Is a photon needed for photoelectric effect?
Yes
288
Is a photon needed for Compton effect?
Yes
289
Is a photon needed for pair production?
Yes
290
Is a photon involved in pair annihilation?
Yes
291
Is a nucleus involved in photoelectric effect?
Not directly
292
Is a nucleus involved in Compton effect?
No
293
Is a nucleus involved in pair production?
Yes
294
Is a nucleus involved in pair annihilation?
No
295
What is the nature of the outcome in photoelectric effect?
Electron emission
296
What is the nature of the outcome in Compton effect?
Particle scattering
297
What is the nature of the outcome in pair production?
Particle creation
298
What is the nature of the outcome in pair annihilation?
Particle destruction
299
What is the outcome of the photoelectric effect?
Ejection of an electron from the metal surface
300
What is the outcome of the Compton effect?
Scattered photon and recoiled electron
301
What is the outcome of pair production?
Creation of an electron and positron
302
What is the outcome of pair annihilation?
Two gamma-ray photons are produced
303
Does the photon survive in the photoelectric effect?
No
304
Does the photon survive in the Compton effect?
Yes
305
Does the photon survive in pair production?
No
306
Does any photon exist before pair annihilation?
No
307
Is mass created in pair production?
Yes
308
Is mass destroyed in pair annihilation?
Yes
309
Are new particles formed in photoelectric effect?
No
310
Are new particles formed in Compton effect?
No
311
Are new particles formed in pair production?
Yes
312
Are new particles formed in pair annihilation?
Yes
313
Is energy converted into mass in photoelectric effect?
No
314
Is energy converted into mass in Compton effect?
No
315
Is energy converted into mass in pair production?
Yes
316
Is mass converted into energy in pair annihilation?
Yes
317
What happens to the photon in the photoelectric effect?
It is fully absorbed by the electron
318
What happens to the photon in Compton effect?
It is scattered with lower energy
319
What happens to the photon in pair production?
It disappears
320
What happens to particles in pair annihilation?
They vanish and convert into photons
321
Does the photoelectric effect involve antimatter?
No
322
Does the Compton effect involve antimatter?
No
323
Does pair production involve antimatter?
Yes
324
Does pair annihilation involve antimatter?
Yes
325
Is momentum conserved in photoelectric effect?
Yes
326
Is momentum conserved in Compton effect?
Yes
327
Is momentum conserved in pair production?
Yes
328
Is momentum conserved in pair annihilation?
Yes
329
What is released in photoelectric effect?
Photoelectron
330
What is released in Compton effect?
Recoil electron and scattered photon
331
What is released in pair production?
Electron and positron
332
What is released in pair annihilation?
Two gamma photons
333
Can photoelectric effect happen with visible light?
Yes
334
Can Compton effect happen with visible light?
No
335
Can pair production happen with visible light?
No
336
Can pair annihilation happen with visible light?
No
337
Is a photon needed for photoelectric effect?
Yes
338
Is a photon needed for Compton effect?
Yes
339
Is a photon needed for pair production?
Yes
340
Is a photon involved in pair annihilation?
Yes
341
Is a nucleus involved in photoelectric effect?
Not directly
342
Is a nucleus involved in Compton effect?
No
343
Is a nucleus involved in pair production?
Yes
344
Is a nucleus involved in pair annihilation?
No
345
What is the nature of the outcome in photoelectric effect?
Electron emission
346
What is the nature of the outcome in Compton effect?
Particle scattering
347
What is the nature of the outcome in pair production?
Particle creation
348
What is the nature of the outcome in pair annihilation?
Particle destruction
349
Wien's law is valid in regions of: (A) Less than lamba max Only (B) Less than lamba mini only (C) Greater than lamba only (D) All of these
A. Less than λₘₐₓ only
350
Wien's law is valid in regions of: (A) Less than lamba max Only (B) Less than lamba mini only (C) Greater than lamba only (D) All of these
A. Less than λₘₐₓ only
351
What is the de Broglie hypothesis?
A: Matter has wave-like properties and every moving particle is associated with a wavelength.
352
What is the de Broglie wavelength of a particle?
A: λ = h / p where h is Planck’s constant and p is momentum.
353
Does a heavier particle have a longer or shorter de Broglie wavelength?
A: Shorter because momentum increases with mass.
354
What is the value of Planck’s constant h?
A: h = 6.626 × 10⁻³⁴ J·s
355
What does the wave-particle duality imply?
A: Every particle exhibits both wave and particle properties.
356
Who proposed the principle of wave-particle duality?
A: Louis de Broglie in 1924.
357
Can wave and particle aspects be observed simultaneously in one experiment?
A: No
358
What is the principle of complementarity?
A: A quantum entity shows either wave or particle nature depending on the experimental setup.
359
What is the conclusion of complementarity in experiments?
A: One aspect appears at a time depending on how the experiment is designed.
360
Which experiment confirmed the wave nature of electrons?
A: Davisson-Germer experiment.
361
In which year was the Davisson-Germer experiment performed?
A: 1927
362
What was observed in the Davisson-Germer experiment?
A: Diffraction pattern of electrons by a nickel crystal.
363
What does diffraction of electrons prove?
A: That electrons exhibit wave properties.
364
What is the condition for constructive interference in electron diffraction?
A: nλ = 2d sinθ
365
What material was used in the Davisson-Germer experiment?
A: A single crystal of nickel.
366
What angle showed maximum electron intensity in the Davisson-Germer experiment?
A: Around 50 degrees for 54 eV electrons.
367
What is the approximate de Broglie wavelength of an electron with 54 eV energy?
A: About 0.167 nm
368
What is the wavelength of visible light?
A: 400 nm to 700 nm
369
What is the typical wavelength of electrons in electron microscopes?
A: About 0.01 nm to 0.001 nm
370
Which microscope uses electrons instead of light?
A: Electron microscope
371
What principle does the electron microscope work on?
A: Wave nature of electrons and their shorter wavelength
372
What is the main advantage of electron microscopes over optical ones?
A: Higher resolution due to smaller wavelength
373
What does resolution depend on?
A: Wavelength of the probing radiation
374
Which component in an electron microscope acts like a lens?
A: Magnetic lens
375
What is the function of the electron gun?
A: It emits and accelerates electrons using high voltage
376
What are the components of the electron gun?
A: Cathode
377
What is a magnetic condenser lens?
A: It focuses the electron beam onto the specimen
378
What is a magnetic objective lens?
A: It forms the primary magnified image of the specimen
379
What does the intermediate image projector do?
A: Further magnifies and projects the image onto a screen or detector
380
What is the torus in an electron microscope?
A: A ring-shaped magnetic coil used for beam focusing
381
What is the tide in electron optics?
A: A distortion or instability in the electron beam
382
What type of vacuum is required in an electron microscope?
A: High vacuum to avoid scattering of electrons
383
What are the two types of electron microscopes?
A: Transmission electron microscope and scanning electron microscope
384
Which electron microscope gives 3D images?
A: Scanning electron microscope (SEM)
385
How does SEM produce images?
A: By scanning the surface with a focused electron beam and collecting secondary electrons
386
What is the magnification power of electron microscopes?
A: Up to 2 million times
387
What is the typical resolution of electron microscopes?
A: About 0.1 nm
388
What is the illumination source in optical microscopes?
A: Visible light
389
What is the illumination source in electron microscopes?
A: Electron beam
390
What is the typical wavelength of X-rays?
A: Around 0.1 nm
391
What is the condition for observing de Broglie waves?
A: Wavelength should be comparable to interatomic spacing (~10⁻¹⁰ m)
392
Can bullets show de Broglie diffraction?
A: No
393
Can a moving pen exhibit de Broglie effects?
A: No
394
Can tuning forks show de Broglie diffraction?
A: No
395
What is the formula for uncertainty in position and momentum?
A: Δx · Δp ≥ ħ / 2
396
What is the formula for uncertainty in energy and time?
A: ΔE · Δt ≥ ħ / 2
397
Who formulated the uncertainty principle?
A: Werner Heisenberg
398
What does the uncertainty principle state?
A: Certain pairs of physical quantities cannot be known simultaneously with precision
399
What does Δx · Δp ≥ ħ / 2 imply?
A: More precise position means less precise momentum and vice versa
400
What does ΔE · Δt ≥ ħ / 2 imply?
A: A system’s energy can fluctuate briefly within the time scale Δt
401
Who won the Nobel Prize for discovering the wave nature of electrons?
A: Louis de Broglie in 1929
402
What is the unit of de Broglie wavelength?
A: Meters (m)
403
What is total uncertainty in quantum terms?
A: Product of uncertainties in complementary variables like position and momentum
404
What happens to de Broglie wavelength as velocity increases?
A: It decreases
405
What is the momentum of a particle?
A: p = mv
406
How do you find de Broglie wavelength for kinetic energy?
A: λ = h / √(2mK)
407
What is the de Broglie wavelength of an electron with 150 eV energy?
A: About 0.1 nm
408
Why do we not observe diffraction of macroscopic objects?
A: Their de Broglie wavelengths are too small
409
What experiment confirmed wave nature of matter?
A: Electron diffraction experiment
410
Is the de Broglie wavelength greater for electrons or protons at same speed?
A: Electrons due to smaller mass
411
How do we increase de Broglie wavelength?
A: Decrease momentum or velocity
412
Is energy-time uncertainty a result of measurement?
A: No
413
What does the scanning coil in SEM do?
A: Deflects the electron beam to scan the surface
414
Why does SEM produce 3D images?
A: Due to variation in secondary electron emission across surface topography
415
What is the principle behind electron diffraction?
A: Wave nature of electrons
416
Why must the microscope column be evacuated?
A: To prevent scattering of electrons by air molecules
417
What is the role of the fluorescent screen in TEM?
A: Converts electron image into visible image
418
Why is wavelength crucial in microscopy?
A: It determines the resolving power
419
Why does shorter wavelength increase resolution?
A: Because diffraction limits are lower
420
What determines the focal length in magnetic lenses?
A: Magnetic field strength
421
Which lens brings electrons to a common point?
A: Magnetic objective lens
422
What is chromatic aberration in electron optics?
A: Image blur due to energy spread in electrons
423
What are secondary electrons?
A: Electrons ejected from specimen atoms during SEM imaging
424
What is backscattered electron imaging?
A: Image formed from electrons reflected back from the specimen
425
What determines SEM image contrast?
A: Composition and topography of the sample
426
What does “aperture” control in an electron microscope?
A: Beam current and resolution
427
How is the electron beam produced?
A: By thermionic or field emission from the cathode
428
What limits the resolution of optical microscopes?
A: Wavelength of visible light
429
What is the resolving power of the human eye?
A: About 0.1 mm
430
What causes the electron to diffract in the Davisson-Germer experiment?
A: Interaction with crystal lattice planes
431
What is the order of magnitude of interatomic spacing?
A: 10⁻¹⁰ m
432
What happens when λ << atomic spacing?
A: No observable diffraction pattern
433
What happens when λ >> atomic spacing?
A: No coherent interference occurs
434
What ensures coherent electron waves in TEM?
A: Monochromatic and collimated electron beam
435
What is the numerical aperture in optics?
A: A measure of the lens’s ability to gather light
436
What does Heisenberg’s principle prevent?
A: Exact prediction of future state of a quantum system
437
What is quantum indeterminacy?
A: The inherent unpredictability of certain measurements
438
Why are de Broglie effects not seen in daily life?
A: Due to extremely short wavelengths for massive objects
439
What is an ideal candidate for observing de Broglie waves?
A: Electrons or atoms at low speeds
440
Why is the electron microscope not suitable for live specimens?
A: Due to vacuum and electron beam damage
441
What does contrast mean in electron microscopy?
A: Difference in detected signal that forms image
442
Why are magnetic fields used instead of glass lenses?
A: Electrons are deflected by magnetic fields not refracted like light
443
What happens to electrons in magnetic lenses?
A: They spiral and focus into a beam
444
What is the advantage of field emission guns?
A: High brightness and coherence
445
What does TEM stand for?
A: Transmission Electron Microscope
446
What does SEM stand for?
A: Scanning Electron Microscope
447
How are electrons accelerated in an electron microscope?
A: By applying high voltage potential
448
What voltage is typically used in TEM?
A: 100 kV to 300 kV
449
What voltage is typically used in SEM?
A: 1 kV to 30 kV
450
What determines the penetration depth of electrons?
A: Their energy
451
What is the direction of the electron beam in a TEM?
A: Perpendicular to the sample and passes through it.
452
What is the direction of the electron beam in SEM?
A: It scans across the surface of the sample.
453
What is meant by coherent electron beam?
A: A beam with electrons of nearly the same energy and phase.
454
What part in TEM converts the electron image to visible image?
A: Fluorescent screen or CCD detector.
455
What is the typical energy range of electrons in TEM?
A: 100 keV to 300 keV.
456
What does high acceleration voltage achieve in TEM?
A: Greater penetration and reduced diffraction.
457
How does specimen thickness affect TEM imaging?
A: Too thick causes multiple scattering and loss of contrast.
458
What is the typical thickness of samples in TEM?
A: Less than 100 nanometers.
459
What is one limitation of SEM?
A: Cannot reveal internal structures.
460
What is one limitation of TEM?
A: Sample must be ultrathin and stable under vacuum.
461
What is one key benefit of SEM?
A: Provides detailed surface topography in 3D.
462
What kind of detector is used in SEM?
A: Secondary electron detector or backscattered detector.
463
What is the role of condenser lens?
A: Focuses beam into a narrow probe before reaching the sample.
464
What is astigmatism in electron optics?
A: Distortion due to unequal focusing in different directions.
465
How is astigmatism corrected?
A: Using stigmator coils in the lens system.
466
What is the purpose of an aperture in the objective lens?
A: To control beam convergence and contrast.
467
What happens to de Broglie wavelength if kinetic energy increases?
A: It decreases due to increased momentum.
468
What is the mass of an electron?
A: 9.11 × 10⁻³¹ kg.
469
What is the charge of an electron?
A: −1.6 × 10⁻¹⁹ C.
470
What is the speed of an electron accelerated through 150V?
A: About 7.27 × 10⁶ m/s.
471
How do you calculate speed of electron from kinetic energy?
A: v = √(2eV/m)
472
What is the de Broglie wavelength of a 1 eV electron?
A: Approximately 1.23 nm.
473
What is the trend between kinetic energy and wavelength?
A: As energy increases
474
How does the microscope achieve magnification?
A: By focusing and enlarging the electron image through magnetic lenses.
475
What is one real-world application of TEM?
A: Studying virus morphology and internal nanostructures.
476
What is one real-world application of SEM?
A: Surface analysis in materials science and forensics.
477
Which microscope has greater depth of field?
A: SEM
478
Which microscope gives internal structure?
A: TEM
479
Which microscope requires sample to be conductive or coated?
A: SEM
480
Why must SEM samples be conductive?
A: To prevent charge build-up from electron beam.
481
What is sputter coating?
A: Applying thin metal layer to non-conductive specimens for SEM imaging.
482
What is the energy source in electron microscopes?
A: High voltage electric field for electron acceleration.
483
Can living cells be observed with electron microscopes?
A: No
484
What is the smallest structure visible under SEM?
A: About 1 nm
485
What is the smallest structure visible under TEM?
A: Less than 0.1 nm
486
What is the refractive index of vacuum?
A: 1
487
What role does wavelength play in resolving power?
A: Shorter wavelength leads to higher resolving power.
488
How are diffraction patterns formed in electron beams?
A: By interference of electron waves scattered by crystal planes.
489
What kind of interaction causes contrast in TEM?
A: Elastic and inelastic scattering of electrons.
490
What is meant by Bragg’s Law in electron diffraction?
A: nλ = 2d sinθ
491
Why do we use ultrathin sections in TEM?
A: To allow electron transmission and reduce scattering.
492
Why is high vacuum necessary in electron microscopy?
A: To prevent collisions with air molecules that deflect the beam.
493
What happens to resolution if beam energy is too low?
A: Resolution decreases due to increased wavelength and scattering.
494
What happens to wavelength if particle speed is very high?
A: Wavelength becomes very small.
495
Why are de Broglie effects not seen in cars?
A: Wavelength is many orders smaller than atomic distances.
496
What is the de Broglie wavelength of a car moving at 20 m/s?
A: Approximately 10⁻³⁷ m
497
What kind of waves are associated with de Broglie hypothesis?
A: Matter waves or matter-associated waves.
498
What is the significance of de Broglie’s theory?
A: It unified wave and particle models for matter.
499
What does it mean for electrons to have dual nature?
A: They behave as both particles and waves depending on observation.
500
Why does the electron beam need to be focused?
A: To form a clear
501
What is an electron diffraction pattern similar to?
A: X-ray diffraction pattern.
502
How is momentum related to wavelength?
A: Inversely
503
What causes quantum uncertainty?
A: The fundamental wave nature of particles.
504
What happens to position certainty as momentum becomes more defined?
A: Position becomes less certain.
505
Can we know the exact position and momentum of an electron?
A: No
506
Why is electron microscopy more suitable for nanostructure analysis?
A: Due to high resolution from short wavelengths.
507
Why does light microscopy fail to resolve below 200 nm?
A: Due to the diffraction limit imposed by visible light wavelength.
508
What is the resolution limit of optical microscopes?
A: Around 200 nm.
509
Which imaging method allows visualization of viruses?
A: Transmission Electron Microscopy (TEM).
510
What happens to the resolving power as wavelength decreases?
A: Resolving power increases.
511
What are backscattered electrons used for?
A: Providing compositional contrast in SEM images.
512
What is the principle behind secondary electron imaging?
A: Emission of low-energy electrons from the surface.
513
What is the result of energy-time uncertainty?
A: Energy measurements become uncertain over short time intervals.
514
Why is Heisenberg uncertainty important in atomic structure?
A: It explains the stability and probabilistic nature of electrons in atoms.
515
How is total uncertainty calculated for position and momentum?
A: As a product of standard deviations: Δx·Δp ≥ ħ/2
516
How is ħ related to h?
A: ħ = h / 2π
517
Why does electron beam require alignment?
A: To avoid distortions and achieve focus.
518
What happens when electron beam alignment is off?
A: Blurred or distorted images.
519
What are the units of de Broglie wavelength?
A: Meters (m).
520
What is the condition for wave-like behavior to be observable?
A: Wavelength must be on the order of system dimensions.
521
What is a vacuum column?
A: The evacuated space in which electrons travel in the microscope.
522
What is the Wehnelt cylinder used for?
A: Shaping and focusing the initial electron beam.
523
What determines the contrast in TEM images?
A: Thickness
524
What is the emission current?
A: Amount of electrons emitted by the electron gun per unit time.
525
How is image magnified in electron microscope?
A: By changing strength of electromagnetic lenses.
526
What is the purpose of intermediate lens in TEM?
A: To adjust image size before projection.
527
What is beam divergence?
A: Spread of electron beam due to defocusing.
528
What causes diffraction fringes in electron images?
A: Coherent interference from crystalline planes.
529
What are inelastic scattered electrons used for?
A: Electron energy loss spectroscopy (EELS).
530
What does high resolution mean in microscopy?
A: Ability to distinguish two closely spaced points.
531
How do electrons interact with matter?
A: Through elastic and inelastic collisions.
532
Why do SEM images appear 3D?
A: Due to signal variation from surface angles and topography.
533
Why can’t we use glass lenses for electrons?
A: Electrons are not refracted by glass
534
How do magnetic fields act like lenses?
A: By causing electron beams to spiral and converge.
535
What is field emission?
A: Electron emission due to high electric field from a sharp tip.
536
What is thermionic emission?
A: Electron release from heated filament.
537
What determines electron velocity in a microscope?
A: The accelerating voltage applied.
538
How is resolution related to numerical aperture?
A: Directly
539
What is energy dispersive X-ray spectroscopy (EDS)?
A: A technique in SEM for elemental analysis.
540
What is diffraction contrast?
A: Image contrast from differences in diffraction from various crystal orientations.
541
What is phase contrast?
A: Imaging based on phase shifts in electron waves.
542
What happens if sample is magnetic?
A: It can distort the electron beam path.
543
What does quantum mechanics replace in atomic theory?
A: Classical mechanics and deterministic predictions.
544
Why are quantum systems probabilistic?
A: Due to wavefunction interpretation and uncertainty principle.
545
What does the wavefunction describe?
A: Probability amplitude of finding a particle at a given point.
546
How is the square of wavefunction interpreted?
A: As the probability density of the particle’s position.
547
What is the direction of the electron beam in a TEM?
A: Perpendicular to the sample and passes through it.
548
What is the direction of the electron beam in SEM?
A: It scans across the surface of the sample.
549
What is meant by coherent electron beam?
A: A beam with electrons of nearly the same energy and phase.
550
What part in TEM converts the electron image to visible image?
A: Fluorescent screen or CCD detector.
551
What is the typical energy range of electrons in TEM?
A: 100 keV to 300 keV.
552
What does high acceleration voltage achieve in TEM?
A: Greater penetration and reduced diffraction.
553
How does specimen thickness affect TEM imaging?
A: Too thick causes multiple scattering and loss of contrast.
554
What is the typical thickness of samples in TEM?
A: Less than 100 nanometers.
555
What is one limitation of SEM?
A: Cannot reveal internal structures.
556
What is one limitation of TEM?
A: Sample must be ultrathin and stable under vacuum.
557
What is one key benefit of SEM?
A: Provides detailed surface topography in 3D.
558
What kind of detector is used in SEM?
A: Secondary electron detector or backscattered detector.
559
What is the role of condenser lens?
A: Focuses beam into a narrow probe before reaching the sample.
560
What is astigmatism in electron optics?
A: Distortion due to unequal focusing in different directions.
561
How is astigmatism corrected?
A: Using stigmator coils in the lens system.
562
What is the purpose of an aperture in the objective lens?
A: To control beam convergence and contrast.
563
What happens to de Broglie wavelength if kinetic energy increases?
A: It decreases due to increased momentum.
564
What is the mass of an electron?
A: 9.11 × 10⁻³¹ kg.
565
What is the charge of an electron?
A: −1.6 × 10⁻¹⁹ C.
566
What is the speed of an electron accelerated through 150V?
A: About 7.27 × 10⁶ m/s.
567
How do you calculate speed of electron from kinetic energy?
A: v = √(2eV/m)
568
What is the de Broglie wavelength of a 1 eV electron?
A: Approximately 1.23 nm.
569
What is the trend between kinetic energy and wavelength?
A: As energy increases
570
How does the microscope achieve magnification?
A: By focusing and enlarging the electron image through magnetic lenses.
571
What is one real-world application of TEM?
A: Studying virus morphology and internal nanostructures.
572
What is one real-world application of SEM?
A: Surface analysis in materials science and forensics.
573
Which microscope has greater depth of field?
A: SEM
574
Which microscope gives internal structure?
A: TEM
575
Which microscope requires sample to be conductive or coated?
A: SEM
576
Why must SEM samples be conductive?
A: To prevent charge build-up from electron beam.
577
What is sputter coating?
A: Applying thin metal layer to non-conductive specimens for SEM imaging.
578
What is the energy source in electron microscopes?
A: High voltage electric field for electron acceleration.
579
Can living cells be observed with electron microscopes?
A: No
580
What is the smallest structure visible under SEM?
A: About 1 nm
581
What is the smallest structure visible under TEM?
A: Less than 0.1 nm
582
What is the refractive index of vacuum?
A: 1
583
What role does wavelength play in resolving power?
A: Shorter wavelength leads to higher resolving power.
584
How are diffraction patterns formed in electron beams?
A: By interference of electron waves scattered by crystal planes.
585
What kind of interaction causes contrast in TEM?
A: Elastic and inelastic scattering of electrons.
586
What is meant by Bragg’s Law in electron diffraction?
A: nλ = 2d sinθ
587
Why do we use ultrathin sections in TEM?
A: To allow electron transmission and reduce scattering.
588
Why is high vacuum necessary in electron microscopy?
A: To prevent collisions with air molecules that deflect the beam.
589
What happens to resolution if beam energy is too low?
A: Resolution decreases due to increased wavelength and scattering.
590
What happens to wavelength if particle speed is very high?
A: Wavelength becomes very small.
591
Why are de Broglie effects not seen in cars?
A: Wavelength is many orders smaller than atomic distances.
592
What is the de Broglie wavelength of a car moving at 20 m/s?
A: Approximately 10⁻³⁷ m
593
What kind of waves are associated with de Broglie hypothesis?
A: Matter waves or matter-associated waves.
594
What is the significance of de Broglie’s theory?
A: It unified wave and particle models for matter.
595
What does it mean for electrons to have dual nature?
A: They behave as both particles and waves depending on observation.
596
Why does the electron beam need to be focused?
A: To form a clear
597
What is an electron diffraction pattern similar to?
A: X-ray diffraction pattern.
598
How is momentum related to wavelength?
A: Inversely
599
What causes quantum uncertainty?
A: The fundamental wave nature of particles.
600
What happens to position certainty as momentum becomes more defined?
A: Position becomes less certain.
601
Can we know the exact position and momentum of an electron?
A: No
602
Why is electron microscopy more suitable for nanostructure analysis?
A: Due to high resolution from short wavelengths.
603
Why does light microscopy fail to resolve below 200 nm?
A: Due to the diffraction limit imposed by visible light wavelength.
604
What is the resolution limit of optical microscopes?
A: Around 200 nm.
605
Which imaging method allows visualization of viruses?
A: Transmission Electron Microscopy (TEM).
606
What happens to the resolving power as wavelength decreases?
A: Resolving power increases.
607
What are backscattered electrons used for?
A: Providing compositional contrast in SEM images.
608
What is the principle behind secondary electron imaging?
A: Emission of low-energy electrons from the surface.
609
What is the result of energy-time uncertainty?
A: Energy measurements become uncertain over short time intervals.
610
Why is Heisenberg uncertainty important in atomic structure?
A: It explains the stability and probabilistic nature of electrons in atoms.
611
How is total uncertainty calculated for position and momentum?
A: As a product of standard deviations: Δx·Δp ≥ ħ/2
612
How is ħ related to h?
A: ħ = h / 2π
613
Why does electron beam require alignment?
A: To avoid distortions and achieve focus.
614
What happens when electron beam alignment is off?
A: Blurred or distorted images.
615
What are the units of de Broglie wavelength?
A: Meters (m).
616
What is the condition for wave-like behavior to be observable?
A: Wavelength must be on the order of system dimensions.
617
What is a vacuum column?
A: The evacuated space in which electrons travel in the microscope.
618
What is the Wehnelt cylinder used for?
A: Shaping and focusing the initial electron beam.
619
What determines the contrast in TEM images?
A: Thickness
620
What is the emission current?
A: Amount of electrons emitted by the electron gun per unit time.
621
How is image magnified in electron microscope?
A: By changing strength of electromagnetic lenses.
622
What is the purpose of intermediate lens in TEM?
A: To adjust image size before projection.
623
What is beam divergence?
A: Spread of electron beam due to defocusing.
624
What causes diffraction fringes in electron images?
A: Coherent interference from crystalline planes.
625
What are inelastic scattered electrons used for?
A: Electron energy loss spectroscopy (EELS).
626
What does high resolution mean in microscopy?
A: Ability to distinguish two closely spaced points.
627
How do electrons interact with matter?
A: Through elastic and inelastic collisions.
628
Why do SEM images appear 3D?
A: Due to signal variation from surface angles and topography.
629
Why can’t we use glass lenses for electrons?
A: Electrons are not refracted by glass
630
How do magnetic fields act like lenses?
A: By causing electron beams to spiral and converge.
631
What is field emission?
A: Electron emission due to high electric field from a sharp tip.
632
What is thermionic emission?
A: Electron release from heated filament.
633
What determines electron velocity in a microscope?
A: The accelerating voltage applied.
634
How is resolution related to numerical aperture?
A: Directly
635
What is energy dispersive X-ray spectroscopy (EDS)?
A: A technique in SEM for elemental analysis.
636
What is diffraction contrast?
A: Image contrast from differences in diffraction from various crystal orientations.
637
What is phase contrast?
A: Imaging based on phase shifts in electron waves.
638
What happens if sample is magnetic?
A: It can distort the electron beam path.
639
What does quantum mechanics replace in atomic theory?
A: Classical mechanics and deterministic predictions.
640
Why are quantum systems probabilistic?
A: Due to wavefunction interpretation and uncertainty principle.
641
What does the wavefunction describe?
A: Probability amplitude of finding a particle at a given point.
642
How is the square of wavefunction interpreted?
A: As the probability density of the particle’s position.
643
What is the main cause of high contrast in electron microscopy?
A: High interaction between electrons and dense atomic nuclei.
644
Why are ultrathin sections cut using a microtome for TEM?
A: To allow electrons to transmit through without excessive scattering.
645
How does increasing beam voltage affect electron wavelength?
A: It reduces the wavelength
646
What limits the visibility of atomic lattices in TEM?
A: Aberrations and electron scattering in thick regions.
647
What is the main cause of high contrast in electron microscopy?
A: High interaction between electrons and dense atomic nuclei.
648
Why are ultrathin sections cut using a microtome for TEM?
A: To allow electrons to transmit through without excessive scattering.
649
How does increasing beam voltage affect electron wavelength?
A: It reduces the wavelength
650
What limits the visibility of atomic lattices in TEM?
A: Aberrations and electron scattering in thick regions.
651
What is the energy of a 100 nm photon?
A: 12.40 eV
652
What is the energy of a 124 nm photon?
A: 10.00 eV
653
What is the energy of a 155 nm photon?
A: 8.00 eV
654
What is the energy of a 200 nm photon?
A: 6.20 eV
655
What is the energy of a 248 nm photon?
A: 5.00 eV
656
What is the energy of a 275 nm photon?
A: 4.51 eV
657
What is the energy of a 300 nm photon?
A: 4.13 eV
658
What is the energy of a 350 nm photon?
A: 3.54 eV
659
What is the energy of a 400 nm photon?
A: 3.10 eV
660
What is the energy of a 450 nm photon?
A: 2.76 eV
661
What is the energy of a 500 nm photon?
A: 2.48 eV
662
What is the energy of a 550 nm photon?
A: 2.25 eV
663
What is the energy of a 600 nm photon?
A: 2.07 eV
664
What is the energy of a 650 nm photon?
A: 1.91 eV
665
What is the energy of a 700 nm photon?
A: 1.77 eV
666
What is the energy of a 750 nm photon?
A: 1.65 eV
667
What is the energy of an 800 nm photon?
A: 1.55 eV
668
What is the energy of a 900 nm photon?
A: 1.38 eV
669
What is the energy of a 1000 nm photon?
A: 1.24 eV
670
What is the energy of a 1200 nm photon?
A: 1.03 eV
671
What is the energy of a 100 nm photon?
A: 12.40 eV
672
What is the energy of a 124 nm photon?
A: 10.00 eV
673
What is the energy of a 155 nm photon?
A: 8.00 eV
674
What is the energy of a 200 nm photon?
A: 6.20 eV
675
What is the energy of a 248 nm photon?
A: 5.00 eV
676
What is the energy of a 275 nm photon?
A: 4.51 eV
677
What is the energy of a 300 nm photon?
A: 4.13 eV
678
What is the energy of a 350 nm photon?
A: 3.54 eV
679
What is the energy of a 400 nm photon?
A: 3.10 eV
680
What is the energy of a 450 nm photon?
A: 2.76 eV
681
What is the energy of a 500 nm photon?
A: 2.48 eV
682
What is the energy of a 550 nm photon?
A: 2.25 eV
683
What is the energy of a 600 nm photon?
A: 2.07 eV
684
What is the energy of a 650 nm photon?
A: 1.91 eV
685
What is the energy of a 700 nm photon?
A: 1.77 eV
686
What is the energy of a 750 nm photon?
A: 1.65 eV
687
What is the energy of an 800 nm photon?
A: 1.55 eV
688
What is the energy of a 900 nm photon?
A: 1.38 eV
689
What is the energy of a 1000 nm photon?
A: 1.24 eV
690
What is the energy of a 1200 nm photon?
A: 1.03 eV
