Magnetic fields & induction worksheet with answers

Free printable Magnetic fields & induction worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
−v = 5 × 10⁶ m/sB = 1 T

An electron moves at 5 × 10⁶ m/s at an angle of 60° to a uniform magnetic field of 1 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 5 × 10⁶ m/sB = 1 Tθ = 60°
F = fN
2.Easy
B0.4 TI = ?45°L = 10 cm

A straight wire 10 cm long lies at 45° to a uniform magnetic field of 0.4 T. The magnetic force on it is 0.08485 N. Find the current I.

B = 0.4 TF = 0.08485 NL = 10 cmθ = 45°
I = A
3.Medium
R = 0.5 Ωv = 5 m/sL = 20 cmB = 0.8 T

A metal rod 20 cm long slides at 5 m/s along two rails in a uniform field of 0.8 T into the page. The rails are joined by a resistor of 0.5 Ω; the rod and rails have negligible resistance. Find the power P dissipated in the resistor.

B = 0.8 TL = 20 cmv = 5 m/sR = 0.5 Ω
P = W
4.Medium
nBA = 40 cm², N = 50B: 0.2 → 1 T

A coil of 50 turns has an area of 40 cm². A uniform field perpendicular to the coil rises steadily from 0.2 T to 1 T in 40 ms. Find the average induced emf ε.

N = 50A = 40 cm²B: 0.2 T → 1 TΔt = 40 ms
ε = V
5.Hard
l = 20 cmN = 200, ⌀ 1.5 cm

A long air-core solenoid has 200 turns, a length of 20 cm and a diameter of 1.5 cm. Find its self-inductance L.

N = 200l = 20 cm⌀ = 1.5 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = µH
6.Hard
V = 2000 VB = 0.3 Tr = ?

An alpha particle starts from rest, is accelerated through a potential difference of 2000 V and then enters a uniform magnetic field of 0.3 T at right angles. Find the radius r of its path in the field.

m = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ CV = 2000 VB = 0.3 T
r = cm

Answer key

  1. 1. F = 693.7 fN
  2. 2. I = 3 A
  3. 3. P = 1.28 W
  4. 4. ε = 4 V
  5. 5. L = 44.41 µH
  6. 6. r = 3.036 cm

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