AcaDec_1920s > Science Section 3 > Flashcards

Science Section 3 Flashcards

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1
Q

When you bend a bar magnet to where you do not have to worry which pole magnetizes metal objects, what do you call it?

A

A horseshoe magnet, which has both poles in one direction. This is the most likely thing you’ll think of when imagining a magnet, too.

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2
Q

Judging by how there are no magnetic monopoles, what produces magnetic fields?

A

Protons and Electrons, however they only appear when a magnetic field is moving.

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3
Q

If a charged particle is not producing a magnetic field but is producing an electric field, what could you say about it’s speed?

A

You would know it is stationary, as stationary charged particles produce an electric field, but no magnetic field strangely.

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4
Q

What two motions do electrons make in an atom that explain why their have their own individual magnetic field?

A

They are always orbiting around the nucleus very quickly, and on top of that are spinning in the process, making it very difficult to not produce one.

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5
Q

Who was the first to notice (and take concern) of the fact that a wire with a running current through it deflects compasses?

A

Hans Christian Oersted in 1820, which is due to the fact that the moving current in a conductor would generate magnetic fields.

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6
Q

Hans Christian Oersted discovered a connection between magnetism and electricity on accident. Why is this myth untrue?

A

It is a myth because he had actually been studying and researching electricity for quite some time.

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7
Q

If an electron is stationary, how would it act around magnetic fields?

A

It would not be affected, as motion is also required for charged particles to feel magnetic forces.

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8
Q

If two current-carrying wires were to be placed together and their directions were correctly placed, how would they potentially effect each other?

A

They could either repel or attract each other.

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9
Q

What differentiates the way magnetic fields and electric fields point?

A

Electric fields point radially away from each other, while magnetic fields always point perpendicular to the direction the charge is moving.

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10
Q

What is the most convenient way to find the direction of the magnetic field if you only know the current’s direction?

A

The Right Hand Rule, where you hold your hand out with all your fingers stretched out, then point your thumb in the current’s directions and your fingers will curl to reveal the direction of the magnetic field.

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11
Q

Why does the rule that all magnetic fields only appear when moving make the magnetic field not fundamental?

A

Because speed is dependent on the observer, meaning it is fundamental.

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12
Q

If you and your friend are watching each other, where your friend is in a train and you are on the ground not moving, what speeds would you be moving to their perspective?

A

You would be moving whatever you perceive the train to the moving, as after 1 hour you both are moving however many miles traveled compared to each other.

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13
Q

At your own frame of reference how fast are you moving

A

You are stationary

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14
Q

If two things are both both moving at different speeds in the same direction how would you find the speed of the faster object relative to the slower objects frame of reference

A

You take the difference of their speeds

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15
Q

relative to the sun how fast is the center of the earth moving

A

70,000 mph or about 100,000 km/hr

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16
Q

relative to the center of the solar system how fast is the center of the sun moving

A

over 100,000 mph and over about 800,000 km/hr

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17
Q

why does the same magnetic field not appear for all frames of references

A

not all frames of references will see electrons moving thus they wont see a magnetic field

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18
Q

Why is magnetic force not a fundamental force

A

over 100,000 mph and over about 800,000 km/hr

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19
Q

why is it that if you do the same experiment at different speeds will you get the same result

A

become with constant movement each objects sees itself as stationary

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20
Q

How fast does the universe move relative to other galaxies in its local group

A

over 300,000 km/hr

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21
Q

how fast does the universe expands

A

70 km/s/Mpc (70 kilometers per second per megaparcepts or 70 km/s per 3.26 million light years)

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22
Q

If two things are both both moving at the same speeds in the same direction how fast is either object moving to the other objects frame of reference

A

The objects is stationary relative to each other

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23
Q

Why do objects that are not moving still feel the effects of gravity

A

Motion is relative, but forces are not

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24
Q

Why If an object is decelerating or accelerating then is it still decelerating or accelerating in its own frame of reference

A

decelerating or accelerating are not relative

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25
How do incandescent lights emit light?
By causing a solid object to heat up enough so that it glows.
26
What was Thomas Edison the first to do with incandescent lights?
He was the first to create a light bulb and build and infrastructure around powering them in cities.
27
What are the two types of magnetic poles?
The two types are north and south poles. Every magnet has both. The north pole of one magnet is attracted to the south pole of another, and the same poles push each other away.
28
How do magnetic poles interact?
Opposite poles attract each other (north to south). Like poles repel each other (north to north or south to south). This is similar to how positive and negative charges work in electricity.
29
What is one main difference between electricity and magnetism?
Electricity has single positive or negative charges (like protons and electrons). Magnetism has no single poles only dipoles, meaning every magnet always has both a north and south pole.
30
What happens if you cut a bar magnet in half?
Each half becomes its own smaller magnet with both a north and south pole. You can’t separate the poles because magnetism always comes in pairs.
31
What is a magnetic dipole?
A magnetic dipole is something that has both a north and south pole. It’s the basic unit of magnetism, found even inside atoms.
32
Do magnetic monopoles exist?
No one has ever found a magnetic monopole. That means there’s no particle that is just a north or just a south pole by itself.
33
Why isn’t there a magnetic version of Coulomb’s law?
Coulomb’s law works for electric charges, but since there are no single magnetic charges, magnetism doesn’t have a similar law. Instead, we describe magnetism using magnetic fields.
34
What do magnetic field lines show around a bar magnet?
The lines show the direction of the magnetic field. They go out from the north pole and curve back into the south pole, forming loops instead of starting or ending anywhere.
35
How does a compass show magnetic fields?
A compass needle lines up with the local magnetic field. The north end of the needle points in the direction of the field, showing which way the magnetic field goes.
36
How do magnetic fields affect charged particles?
Magnetic fields push on moving charged particles like electrons and protons. The force changes the direction of their motion, not their speed.
37
What makes an object magnetic on a large scale?
If the tiny atomic magnets inside the object all line up in the same direction, their magnetic fields add together, making the whole object act like a magnet.
38
Why are most materials not magnetic?
Their atomic magnets point in random directions, canceling each other out. Since the small fields don’t line up, the material shows no magnetism overall.
39
What are ferromagnetic materials?
Ferromagnetic materials, like iron and nickel, can have their atoms lined up by a strong magnetic field. Once lined up, they stay that way, forming a permanent magnet.
40
the sun fips it's magnetic poles roughly 1 time in how many years
eleven years
41
when the sun's poles are about to switch, what may appear on it's surface
sunspots
42
How do CME's (Coronal mass ejections) happen?
the magnetic fied on the sun get's so twisted that it stretches out, ausing bits of the sun to fly off
43
what was the Carrington Event caused by
a CME hitting the Earth
44
when was the last solar maximum
45839
45
How are magentic force and electric force similar?
they are proportional to the electric charge and to their respective fields, magnetic and electric
46
What does magnetic force mostly concern?
direction
47
When is the direction of the electric force the same as the electric field? (Hint: think of the charge of the particles)
for positively charged particles
48
When is the direction of the electric force the opposite as the electic field?
for negatively charged particles
49
What is the direction of the magetic force in respects to the magnetic field?
perpendicular
50
What two vectors is the magentic force perpendicular to?
the magnetic field and velocity of the object
51
If the direction of the magnetic force is perpendicular to the magetnic field and velocity of the charged particle, what is the direction of the charged particle in respect to the magnetic field?
it is also perpendicular
52
What does it mean for the magnetic force to be a "three-dimensional force"?
the magetic force vector F(sub B) is perpendicular to the two-dimesnional plane formed by the velocity (v) and magnetic field (B) vectors
53
What must be true about a charged particle's motion for magnetic force to exist?
the particle must be moving and it must be movign in a different direction than the magnetic field
54
How can we determine the direction of the magnetic force using our hands?
via the right-hand rule
55
What sort of gesture should your right hand be in to determine the direction of the magnetic force via the right-hand rule?
a "finger gun" gesture where your index and thumb are pointing particular (making the gun) while the rest of your fingers are pointing perpedicular to your index finger (facing towards you)
56
Using the right-hand rule, how many and what axis are created by your fingers?
3; x, y, & z axis
57
Using the right-hand rule, what does your index finger represent?
the velocity direction (or the direction in which the charged particle is moving)
58
Using the right-hand rule, what does your thumb represent?
the direction of the resulting force
59
Using the right-hand rule, what do the rest of your fingers (besides the thumb and index finger) represent?
the direction of the magnetic field
60
True or False? Magnetic fields speed or slow down charged particles
False; magnetic fields deflect charged particles
61
What is a solenoid?
Wire that forms multiple circular loops on top of each other.
62
What is the symbol for permeability of free space?
μ₀
63
Which way does a magnetic field go?
It moves counterclockwise
64
Compare the magnetic field of a solenoid and a bar magnet?
They look identical.
65
What is the equation for the magnetic field inside a solenoid using Ampere's law?
B=μ₀I(N/L)
66
What are most solenoids used for?
Miniature solenoids are used in all kinds of electric circuits. On a larger scale, the tube in an MRI machine is a giant solenoid.
67
How powerful is the magnetic field produced from the currents of a MRI machine?
The magnetic field of a MRI machine can range between 1 and 2 Telsa.
68
What could happen if there are metal objects in the vicinity of an MRI machine?
The metal objects can become dangerous projectiles because they become magnetized and pulled by the magnetic field.
69
What event regarding MRI machines occured at a hospital in Redwood City in 2023?
Metallic medical equipment was pulled in towards an active MRI machine, this happened because the equipment was not put far enough away from the machine.
70
How can you use magnets to generate current?
You would need a changing magnetic field, this is because a magnetic field will only affect a charge if the charge is moving. (Discovered by Michael Faraday in 1831)
71
Who did Michael Faraday eventually work for as a lab assistant?
Humphrey Davy, a famed chemist.
72
Why did Faraday resist monetary awards and accolades?
Accumulating wealth went against his religious beliefs.
73
What is the centripetal force?
a force that does not change the speed of an object but only changes the object's direction
74
What results from the magnetic force deflecting particles rather than changing their speed?
a circular motion
75
What can a mass spectrometer be used for?
to determine the atomic composition of an unknown sample
76
Who discovered the electron? When?
J.J. Thomson in 1897
77
How is a mass spectrometer used to determine the atomic composition of an unknown sample? Explain the steps.
First, the sample is vaporized which creates an ionic gas. Next, the ions are accelerated by a voltage. Then, the ions will move into a magnetic field where they are deflected into a circle. Where the ions land let's us know which element the ion is
78
Where the ions land when performing the mass spectrometer experiment depend on what?
the charge and mass of ion
79
True or False? Wires with electric current will also feel a magnetic force
t
80
Who is Ampere's Law and the units of current named after?
Andre-Marie Amere
81
What are the units of current?
the Ampere
82
What was the profession of Andre-Marie Ampere?
French physicist
83
What can Ampere's Law be used for?
to determine what the magnetic fields around objects look like
84
What do we draw to determine what magnetic fields around objects look like using Ampere's Law?
Amperian loops to observe how the magnetic field changes (if it even does)along the loops
85
Why did the feud between Edison and George Westinghouse begin?
George Westinghouse founded his own electric company and lit up a town with alternating current.
86
Who was the arc lamp invented by?
The arc lamp, which is the first widespread electric lamp, was invented by the chemist Humphery Davy.
87
What did Mikhail Dolivo-Dobrovolsky invent in 1891?
A three-phase generator. This allowed an efficient transfer of current over long distances using AC.
88
What did Alexander Just and Franjo Hanaman createin 1904?
The tungsten lightbulb. The tungsten lightbulb turned out to be more efficient and longer lasting than the carbon ones Edison made and eventually became the international standard.
89
What does the Tesla coil do?
The Tesla coil creates a high voltage on a metal ball on top of a coil of wire.
90
What is a solenoid?
Multiple loops of wire wrapped around on top of each other, creating a cylinder of one continuous loop of wire.
91
What does an inductor do?
Resists any changes of current within a circuit, allowing current to increase or decrease gradually rather than instantly.
92
Which rule does the magnetic force follow?
The magnetic force follows the “right-hand rule,” which helps us visualize the three vectors involved (force, velocity, and magnetic field) that all point in perpendicular directions.
93
What is believed about the Earth's core?
The core of the Earth is believed to be a giant ball of molten iron, which creates a planet-wide magnetic field.
94
What does Earth's magnetic field do?
The Earth’s magnetic field protects us from potentially harmful particles from outer space. The particles that make it to Earth are deflected toward the poles and light up the sky, creating the aurora.
95
What are the three different types of things we can connect ot a power source in a basic circuit?
a resistor, a capacitor, and an inductor
96
What would happen to the capacitor if you only connected a charged capacitor to an inductor with no power source?
the capacitor will start to discharge, and current will flow through the conductor. This causes the current to gradually die down/run out as the capacitor neutralizes
97
How would the inductor react when it is connected to a charged capacitor with no power source?
it’ll resist this decrease in current and create a magnetic field that induces counter-current, even after the capacitor discharges
98
What is the result of an inductor resisting the decrease in current and inducing a counter-current caused by a charged capacitor being connected to the inductor with no power source?
it recharges the capacitor, but from an opposite orientation
99
How is the pattern between a charged capacitor connected to an inductor just a repeating cycle?
becuase after the capacitor originally discharges, it is recharged by the inductor, but once it is fully charged, then it will discharge again; restarting the cycle
100
The back-and-forth cycle between a connected charged capacitor and inductor with no power source is analogous to?
the swing of a pendulum
101
What is the purpose of an inductor and a capacitor in an RLC circuit?
to work together to keep the current oscillating back and forth
102
What is the equation that shows the frequency at which an RLC circuit oscillates?
f = 1/(2π(square root of (LC))
103
What does the C variable represent in the equation for determining the frequency at which a circuit oscillates?
the capacito
104
What does the L variable represent in the equation for determining the frequency at which a circuit oscillates?
the inductance of the inductor
105
The inductance of the inductor (L) and the capacitor (C ) both depend on the?
physical characteristics of the objects
106
What is resonance?
a property of many different oscillating systems
107
What is the frequency at which an RLC circuit oscillates also known as?
the natural, or resonant, frequency
108
What will you get if you connect a capacitor-inductor circuit to an AC power source that alternates with a frequency matching the circuit itself?
maximum current
109
According to Lenz’s Law, what does the magnetic field in a solenoid do?
It opposes any external change in magnetic flux.
110
Why can’t a generator run indefinitely without input energy?
Because the opposing magnetic field creates a resisting force, requiring constant energy input.
111
What is the purpose of a transformer?
To step voltage up or down between circuits using electromagnetic induction.
112
What does the primary coil in a transformer do?
It is connected to a power source and creates a changing magnetic field.
113
What does the secondary coil in a transformer do?
It has no direct power source but induces voltage from the magnetic field of the primary coil.
114
Why must the current in the primary coil be alternating (AC)?
Because only a changing magnetic field induces a voltage in the secondary coil.
115
What is the equation relating voltage and number of coil loops in a transformer?
N1​V1​​=N2​V2​​
116
If the secondary coil has more loops than the primary, what happens to the voltage?
The voltage increases (step-up transformer), but current decreases due to higher resistance.
117
Why are high voltages used in power lines?
To reduce current and minimize energy loss as heat over long distances.
118
How do transformers make power safe for homes?
They step down high transmission voltages to around 120 V for domestic use.
119
What kind of current do most household outlets provide?
Alternating Current (AC).
120
What does a diode do in an AC circuit?
It allows current to flow in only one direction, converting AC to DC.
121
How does a capacitor smooth AC into DC?
By charging and discharging as current changes direction, creating a steadier output.
122
What does an inductor do in a circuit?
It resists changes in current by creating an opposing magnetic field (self-induction).
123
Why should you turn a device off before unplugging it?
Because inductors can cause a spark as they try to keep current flowing when the circuit is broken.
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