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 12 A at an angle of 60° to a uniform magnetic field of 1.2 T. Find the magnitude of the force F on the wire.

B = 1.2 TI = 12 AL = 25 cmθ = 60°

F = N

2.Easy

A rectangular loop of 10 cm by 30 cm lies in a uniform magnetic field of 0.05 T. The field makes an angle of 60° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 0.05 TA = 10 cm × 30 cm60° to the normal

Φ = mWb

3.Medium

Two long parallel wires 3 cm apart carry currents of 10 A and 30 A in the same direction. Find the force per metre of length F/L between them.

I₁ = 10 AI₂ = 30 Ad = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A

F/L = µN/m

4.Medium

A metal rod 40 cm long slides at 2.5 m/s along two rails in a uniform field of 0.4 T into the page. Find the induced emf ε between its ends.

B = 0.4 TL = 40 cmv = 2.5 m/s

ε = mV

5.Hard

The current in a 25 mH inductor changes steadily from 0 A to 3 A in 10 ms. Find the magnitude of the self-induced emf ε.

L = 25 mH0 A → 3 AΔt = 10 ms

ε = V

6.Hard

A deuteron starts from rest, is accelerated through a potential difference of 1000 V and then enters a uniform magnetic field of 0.25 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 = 1000 VB = 0.25 T

r = cm

Answer key

1. F = 3.118 N
2. Φ = 0.75 mWb
3. F/L = 2000 µN/m
4. ε = 400 mV
5. ε = 7.5 V
6. r = 2.585 cm

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