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 1 A at an angle of 60° to a uniform magnetic field of 0.1 T. Find the magnitude of the force F on the wire.

B = 0.1 TI = 1 AL = 25 cmθ = 60°

F = N

2.Easy

A straight wire 10 cm long lies at 90° to a uniform magnetic field of 0.4 T. The magnetic force on it is 0.6 N. Find the current I.

B = 0.4 TF = 0.6 NL = 10 cmθ = 90°

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 20 turns has an area of 10 cm². The coil is turned over (rotated through 180°) in a uniform field of 0.1 T, which is perpendicular to its plane, in 20 ms. Find the average induced emf ε.

N = 20A = 10 cm²B = 0.1 TΔt = 20 ms

ε = mV

5.Hard

A coil of 150 turns, 10 cm × 20 cm, rotates at 1500 rpm in a uniform field of 0.25 T about an axis perpendicular to the field. Find the rms value E_rms of the emf.

N = 150A = 10 cm × 20 cmB = 0.25 Tn = 1500 rpm

E_rms = V

6.Hard

A long air-core solenoid has 200 turns, a length of 10 cm and a diameter of 4 cm. Find its self-inductance L.

N = 200l = 10 cm⌀ = 4 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = µH

Answer key

1. F = 0.02165 N
2. I = 15 A
3. counterclockwise
4. ε = 200 mV
5. E_rms = 83.3 V
6. L = 631.7 µH

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