Formula sheet Knowledge 2

Question 1

What is the formula F = qE and what are its variables?,

Answer 1

**“Force on a charge in an electric field. **F = qE, where
F = force (N),
q = charge (C),
E = electric field (N/C).”

Question 2

What is the formula Fe = k q₁q₂ / r² and what are its variables?,

Answer 2

“**Coulomb’s law. **Fe = k q₁q₂ / r²,
where
Fe = electrostatic force (N),
k = Coulomb’s constant,
q₁ & q₂ = charges (C),
r = separation (m).”

Question 3

What is the formula E=V/d and what are its variables?,

Answer 3

“Electric field strength. E=V/d,
where
V = potential difference (V),
E = electric field (N/C),
d = separation (m).”

Question 4

What is the formula V = W/q and what are its variables?,

Answer 4

“Potential difference as work per charge. V = W/q,
where
V = potential difference (V),
W = work done (J),
q = charge (C).”

Question 5

What is the formula I = Δq/Δt and what are its variables?,”

Answer 5

Current as rate of flow of charge. I = Δq/Δt, where
I = current (A),
Δq = charge (C),
Δt = time (s).”

Question 6

What is the formula P = VI and what are its variables?,

Answer 6

“Electrical power. P = VI,
where
P = power (W)
V = potential difference (V)
I = current (A).”

Question 7

What is the formula B = μ₀I / (2πr) and what are its variables?,

Answer 7

“**Magnetic field around a long straight conductor. **B = μ₀I/(2πr),
where
B = magnetic field (T),
μ₀ = permeability of free space,
I = current (A),
r = distance from wire (m).”

Question 8

What is the formula F = qvB and what are its variables?,

Answer 8

“Magnetic force on a moving charge. F = qvB,
where
F = force (N)
q = charge (C),
v = velocity (m/s),
B = magnetic field (T).”

Question 9

What is the formula F = BIL and what are its variables?,

Answer 9

“**Force on a current-carrying conductor. **
F = BIL,
where
F = force (N),
B = magnetic field (T),
I = current (A),
L = length of conductor (m).”

Motor effect

Question 10

What is the formula Φ = BA and what are its variables?,

Answer 10

“Magnetic flux. Φ = BA,
where
Φ = flux (Wb),
B = magnetic field (T),
A = area (m²).”

Question 11

What is the formula ε = -N ΔΦ/Δt and what are its variables?,

Answer 11

“Faraday’s law of electromagnetic induction. ε = -N ΔΦ/Δt,
where
ε = emf (V),
N = number of turns,
ΔΦ/Δt = rate of change of flux.”

Question 12

What is the formula τ = nIAB and what are its variables?,”

Answer 12

Torque on a current-carrying coil. τ = nIAB,
where
τ = torque (Nm),
n = number of turns,
I = current (A),
A = area (m²),
B = magnetic field (T).”

sinθ angle to the normal plane

Question 13

What is the formula W = qV and what are its variables?,”

Answer 13

Work done by an electric field. W = qV, where
W = work (J),
q = charge (C),
V = potential difference (V).”

Question 14

What is the formula Ek = ½mv² and what are its variables?,”

Answer 14

**Kinetic energy of a particle. **Ek = ½mv²,
where
m = mass (kg),
v = velocity (m/s).”

Question 15

What is the formula p = mv and what are its variables?,”

Answer 15

Momentum. p = mv,
where
p = momentum (kg·m/s),
m = mass (kg),
v = velocity (m/s).”

Question 16

What is the formula E = hf and what are its variables?,

Answer 16

“Photon energy. E = hf,
where
E = energy (J),
h = Planck’s constant,
f = frequency (Hz).”

Planks formula

Question 17

What is the formula c = fλ and what are its variables?,”

Answer 17

Wave equation. c = fλ,
where
c = speed of light (3×10⁸ m/s),
f = frequency (Hz),
λ = wavelength (m).”

Question 18

What is the formula E = mc² and what are its variables?,”

Answer 18

Mass–energy equivalence. E = mc²,
where
E = energy (J),
m = mass (kg),
c = speed of light.”

Einsteins equation

Question 19

What is the formula p = h/λ and what are its variables?,”

Answer 19

de Broglie wavelength. λ = h/p,
where
λ = wavelength (m),
h = Planck’s constant,
p = momentum (kg·m/s).”

Question 20

What is the formula N(t) = N₀e^(-λt) and what are its variables?,”

Answer 20

**Radioactive decay law. **N(t) = N₀e^(-λt),
where
N = number of nuclei remaining,
N₀ = initial number,
λ = decay constant (s⁻¹), t = time (s).”

Question 21

What is the formula A = λN and what are its variables?,”

Answer 21

Activity of a radioactive sample. A = λN,
where
A = activity (Bq),
λ = decay constant (s⁻¹),
N = number of nuclei.”

Question 22

What is the formula λ = ln(2)/t½ and what are its variables?,”

Answer 22

Decay constant–half life relationship.
λ = ln(2)/t½,
where
λ = decay constant (s⁻¹),
t½ = half-life (s).”

Question 23

What is the formula L = L₀√(1 - v²/c²) and what are its variables?,

Answer 23

“Length contraction. L = L₀√(1 - v²/c²),
where
L = contracted length (m),
L₀ = proper length (m),
v = relative velocity (m/s),
c = speed of light (m/s).”

only contraction in the direction of movement (ie height not affected)

Question 24

What is the formula
t = t₀ / √(1 - v²/c²)
and what are its variables?,

Answer 24

“Time dilation. t = t₀/√(1 - v²/c²),
where
t = dilated time (s),
t₀ = proper time (s),
v = relative velocity (m/s),
c = speed of light (m/s).”

Tics take longer at speed

Question 25

What is the formula p = mv / √(1 - v²/c²) and what are its variables?,

Answer 25

"**Relativistic momentum.** p = mv/√(1 - v²/c²), where p = relativistic momentum (kg·m/s), m = rest mass (kg), v = velocity (m/s), c = speed of light (m/s)." ## Footnote Consequence: establishment of the speed of light as the universal speed limit for objects with mass, as it would require infinite energy to accelerate a massive object to the speed of light, resulting in infinite momentum.