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 alpha particle moves at 4 × 10⁶ m/s at an angle of 60° to a uniform magnetic field of 0.02 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 4 × 10⁶ m/sB = 0.02 Tθ = 60°

F = fN

2.Easy

A long straight wire carries a current of 4 A. Find the magnetic flux density B at point P, 15 cm from the wire.

I = 4 Ar = 15 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

3.Medium

A coil of 100 turns has an area of 10 cm². A uniform field perpendicular to the coil rises steadily from 0 T to 0.5 T in 200 ms. Find the average induced emf ε.

N = 100A = 10 cm²B: 0 T → 0.5 TΔt = 200 ms

ε = mV

4.Medium

A coil of 25 turns has an area of 40 cm². The coil is turned over (rotated through 180°) in a uniform field of 0.3 T, which is perpendicular to its plane, in 100 ms. Find the average induced emf ε.

N = 25A = 40 cm²B = 0.3 TΔt = 100 ms

ε = mV

5.Hard

A coil of 20 turns, 12 cm × 10 cm, rotates at 600 rpm in a uniform field of 0.05 T about an axis perpendicular to the field. Find the peak emf E₀.

N = 20A = 12 cm × 10 cmB = 0.05 Tn = 600 rpm

E₀ = V

6.Hard

The current in a 100 mH inductor changes steadily from 1 A to 0 A in 5 ms. Find the magnitude of the self-induced emf ε.

L = 100 mH1 A → 0 AΔt = 5 ms

ε = V

Answer key

1. F = 22.2 fN
2. B = 5.333 µT
3. ε = 250 mV
4. ε = 600 mV
5. E₀ = 0.754 V
6. ε = 20 V

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