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

A proton moves at 6 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.02 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 6 × 10⁶ m/sB = 0.02 Tθ = 90°

F = fN

2.Easy

A long straight wire carries a current of 40 A. Find the magnetic flux density B at point P, 12 cm from the wire.

I = 40 Ar = 12 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

3.Medium

A coil of 500 turns, area 25 cm² and resistance 2 Ω forms a closed circuit. A uniform field perpendicular to the coil rises steadily from 0.1 T to 0.7 T in 500 ms. Find the average induced current I.

N = 500A = 25 cm²B: 0.1 T → 0.7 TΔt = 500 msR = 2 Ω

I = mA

4.Medium

A coil of 100 turns has an area of 200 cm². The coil sits in a uniform field of 0.3 T perpendicular to its plane, and the field is switched off in 40 ms. Find the average induced emf ε.

N = 100A = 200 cm²B = 0.3 TΔt = 40 ms

ε = V

5.Hard

A long air-core solenoid has 500 turns, a length of 15 cm and a diameter of 3 cm. Find its self-inductance L.

N = 500l = 15 cm⌀ = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = mH

6.Hard

A short coil of 20 turns is wound tightly round the middle of a long solenoid of 2000 turns, length 40 cm and diameter 5 cm. Find their mutual inductance M.

N₁ = 2000N₂ = 20l = 40 cm⌀ = 5 cmμ₀ = 4π × 10⁻⁷ T·m/A

M = µH

Answer key

1. F = 19.22 fN
2. B = 66.67 µT
3. I = 750 mA
4. ε = 15 V
5. L = 1.48 mH
6. M = 246.7 µH

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