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 80 cm long lies at 60° to a uniform magnetic field of 0.1 T. The magnetic force on it is 1.039 N. Find the current I.

B = 0.1 TF = 1.039 NL = 80 cmθ = 60°

I = A

2.Easy

A flat circular coil of 100 turns and radius 4 cm carries a current of 3 A. Find the magnetic flux density B at its centre.

N = 100I = 3 AR = 4 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = mT

3.Medium

An alpha particle moving at 6 × 10⁵ m/s enters a uniform magnetic field at right angles and moves on a circle of radius 1.555 cm. Find the magnetic flux density B.

m = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ Cv = 6 × 10⁵ m/sr = 1.555 cm

B = T

4.Medium

A circular loop lies in a uniform magnetic field pointing into the page. The field strength is increasing. Click the direction of the induced current in the loop as seen in the drawing.

B: into the pagedB/dt > 0

1clockwise
2counterclockwise

5.Hard

A coil of 50 turns, 8 cm × 15 cm, rotates at 300 rpm in a uniform field of 0.25 T about an axis perpendicular to the field. Find the peak emf E₀.

N = 50A = 8 cm × 15 cmB = 0.25 Tn = 300 rpm

E₀ = V

6.Hard

A long air-core solenoid has 2000 turns, a length of 15 cm and a diameter of 4 cm. Find its self-inductance L.

N = 2000l = 15 cm⌀ = 4 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = mH

Answer key

1. I = 15 A
2. B = 4.712 mT
3. B = 0.8002 T
4. counterclockwise
5. E₀ = 4.712 V
6. L = 42.11 mH

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