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 30 cm long carries 20 A at an angle of 90° to a uniform magnetic field of 0.12 T. Find the magnitude of the force F on the wire.

B = 0.12 TI = 20 AL = 30 cmθ = 90°

F = N

2.Easy

A straight wire 40 cm long carries 1 A at an angle of 90° to a uniform magnetic field of 0.05 T. Find the magnitude of the force F on the wire.

B = 0.05 TI = 1 AL = 40 cmθ = 90°

F = N

3.Medium

A coil of 25 turns has an area of 50 cm². A uniform field perpendicular to the coil rises steadily from 0.05 T to 0.85 T in 10 ms. Find the average induced emf ε.

N = 25A = 50 cm²B: 0.05 T → 0.85 TΔt = 10 ms

ε = V

4.Medium

An electron moving at 5 × 10⁶ m/s enters a uniform magnetic field at right angles and moves on a circle of radius 1.137 cm. Find the magnetic flux density B.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ Cv = 5 × 10⁶ m/sr = 1.137 cm

B = mT

5.Hard

A deuteron starts from rest, is accelerated through a potential difference of 500 V and then enters a uniform magnetic field of 0.4 T at right angles. Find the radius r of its path in the field.

m = 3.344 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 500 VB = 0.4 T

r = cm

6.Hard

The current in a 500 mH inductor changes steadily from 1 A to 6 A in 2 ms. Find the magnitude of the self-induced emf ε.

L = 500 mH1 A → 6 AΔt = 2 ms

ε = V

Answer key

1. F = 0.72 N
2. F = 0.02 N
3. ε = 10 V
4. B = 2.5 mT
5. r = 1.142 cm
6. ε = 1250 V

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