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 rectangular loop of 12 cm by 10 cm lies in a uniform magnetic field of 0.5 T. The field makes an angle of 37° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 0.5 TA = 12 cm × 10 cm37° to the normal

Φ = mWb

2.Easy

A straight wire 20 cm long carries 12 A at an angle of 90° to a uniform magnetic field of 0.4 T. Find the magnitude of the force F on the wire.

B = 0.4 TI = 12 AL = 20 cmθ = 90°

F = N

3.Medium

A coil of 25 turns, area 10 cm² and resistance 20 Ω forms a closed circuit. A uniform field perpendicular to the coil rises steadily from 0.2 T to 0.3 T in 500 ms. Find the average induced current I.

N = 25A = 10 cm²B: 0.2 T → 0.3 TΔt = 500 msR = 20 Ω

I = mA

4.Medium

A coil of 20 turns has an area of 80 cm². The coil is turned over (rotated through 180°) in a uniform field of 0.8 T, which is perpendicular to its plane, in 200 ms. Find the average induced emf ε.

N = 20A = 80 cm²B = 0.8 TΔt = 200 ms

ε = V

5.Hard

A coil of 150 turns, 12 cm × 15 cm, rotates at 1500 rpm in a uniform field of 0.1 T about an axis perpendicular to the field. Find the rms value E_rms of the emf.

N = 150A = 12 cm × 15 cmB = 0.1 Tn = 1500 rpm

E_rms = V

6.Hard

The current in a 50 mH inductor changes steadily from 0 A to 1 A in 10 ms. Find the magnitude of the self-induced emf ε.

L = 50 mH0 A → 1 AΔt = 10 ms

ε = V

Answer key

1. Φ = 4.792 mWb
2. F = 0.96 N
3. I = 0.25 mA
4. ε = 1.28 V
5. E_rms = 29.99 V
6. ε = 5 V

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