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 single circular loop of wire with radius 6 cm carries a current of 3 A. Find the magnetic flux density B at its centre.

N = 1I = 3 AR = 6 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

2.Easy

The magnetic flux density 1 cm from a long straight wire is 200 µT. Find the current I in the wire.

B = 200 µTr = 1 cmμ₀ = 4π × 10⁻⁷ T·m/A

I = A

3.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

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 0.1 T, which is perpendicular to its plane, in 50 ms. Find the average induced emf ε.

N = 250A = 100 cm²B = 0.1 TΔt = 50 ms

ε = V

5.Hard

A coil of 150 turns, 12 cm × 20 cm, rotates at 900 rpm in a uniform field of 0.3 T about an axis perpendicular to the field. Find the rms value E_rms of the emf.

N = 150A = 12 cm × 20 cmB = 0.3 Tn = 900 rpm

E_rms = V

6.Hard

A coil of 200 turns, 15 cm × 25 cm, rotates at 900 rpm in a uniform field of 0.3 T about an axis perpendicular to the field. Find the peak emf E₀.

N = 200A = 15 cm × 25 cmB = 0.3 Tn = 900 rpm

E₀ = V

Answer key

1. B = 31.42 µT
2. I = 10 A
3. counterclockwise
4. ε = 10 V
5. E_rms = 71.97 V
6. E₀ = 212.1 V

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