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 8 × 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| = 1.602 × 10⁻¹⁹ Cv = 8 × 10⁶ m/sB = 0.02 Tθ = 60°

F = fN

2.Easy

A straight wire 25 cm long carries 10 A at an angle of 45° to a uniform magnetic field of 0.08 T. Find the magnitude of the force F on the wire.

B = 0.08 TI = 10 AL = 25 cmθ = 45°

F = N

3.Medium

A proton moves at 4 × 10⁵ m/s perpendicular to a uniform magnetic field of 0.25 T. Find the radius r of its circular path.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ Cv = 4 × 10⁵ m/sB = 0.25 T

r = cm

4.Medium

A coil of 250 turns has an area of 100 cm². The coil is turned over (rotated through 180°) in a uniform field of 0.3 T, which is perpendicular to its plane, in 200 ms. Find the average induced emf ε.

N = 250A = 100 cm²B = 0.3 TΔt = 200 ms

ε = V

5.Hard

A long air-core solenoid has 300 turns, a length of 25 cm and a diameter of 4 cm. Find the energy W stored in its magnetic field when it carries 4 A.

N = 300l = 25 cm⌀ = 4 cmI = 4 Aμ₀ = 4π × 10⁻⁷ T·m/A

W = mJ

6.Hard

A proton starts from rest, is accelerated through a potential difference of 500 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 = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 500 VB = 0.25 T

r = cm

Answer key

1. F = 22.2 fN
2. F = 0.1414 N
3. r = 1.671 cm
4. ε = 7.5 V
5. W = 4.548 mJ
6. r = 1.293 cm

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