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 straight wire 25 cm long carries 20 A at an angle of 30° to a uniform magnetic field of 0.4 T. Find the magnitude of the force F on the wire.

B = 0.4 TI = 20 AL = 25 cmθ = 30°

F = N

2.Easy

An alpha particle moves at 5 × 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 = 5 × 10⁶ m/sB = 0.02 Tθ = 60°

F = fN

3.Medium

An electron moves on a circle in a uniform magnetic field of 1 mT. Find the time T it takes for one revolution.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ CB = 1 mT

T = ns

4.Medium

A coil of 25 turns, area 40 cm² and resistance 2 Ω forms a closed circuit. A uniform field perpendicular to the coil rises steadily from 0 T to 0.4 T in 500 ms. Find the average induced current I.

N = 25A = 40 cm²B: 0 T → 0.4 TΔt = 500 msR = 2 Ω

I = mA

5.Hard

A coil of 200 turns, 10 cm × 10 cm, rotates at 600 rpm in a uniform field of 0.3 T about an axis perpendicular to the field. Find the rms value E_rms of the emf.

N = 200A = 10 cm × 10 cmB = 0.3 Tn = 600 rpm

E_rms = V

6.Hard

A long air-core solenoid has 800 turns, a length of 25 cm and a diameter of 3 cm. Find its self-inductance L.

N = 800l = 25 cm⌀ = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = mH

Answer key

1. F = 1 N
2. F = 27.75 fN
3. T = 35.73 ns
4. I = 40 mA
5. E_rms = 26.66 V
6. L = 2.274 mH

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