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

An electron moves at 6 × 10⁶ m/s at an angle of 30° to a uniform magnetic field of 0.1 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 6 × 10⁶ m/sB = 0.1 Tθ = 30°

F = fN

2.Easy

An electron moves at 4 × 10⁶ m/s at an angle of 45° to a uniform magnetic field of 1 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 4 × 10⁶ m/sB = 1 Tθ = 45°

F = fN

3.Medium

A coil of 50 turns has an area of 20 cm². The coil is turned over (rotated through 180°) in a uniform field of 0.1 T, which is perpendicular to its plane, in 250 ms. Find the average induced emf ε.

N = 50A = 20 cm²B = 0.1 TΔt = 250 ms

ε = mV

4.Medium

An alpha particle moves at 8 × 10⁶ m/s perpendicular to a uniform magnetic field of 1.5 T. Find the radius r of its circular path.

m = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ Cv = 8 × 10⁶ m/sB = 1.5 T

r = cm

5.Hard

A coil of 200 turns, 10 cm × 25 cm, rotates at 3000 rpm in a uniform field of 0.25 T about an axis perpendicular to the field. Find the rms value E_rms of the emf.

N = 200A = 10 cm × 25 cmB = 0.25 Tn = 3000 rpm

E_rms = V

6.Hard

A long air-core solenoid has 800 turns, a length of 15 cm and a diameter of 3 cm. Find its self-inductance L.

N = 800l = 15 cm⌀ = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = mH

Answer key

1. F = 48.06 fN
2. F = 453.1 fN
3. ε = 80 mV
4. r = 11.06 cm
5. E_rms = 277.7 V
6. L = 3.79 mH

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