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
B1.2 T5 A90°L = 15 cm

A straight wire 15 cm long carries 5 A at an angle of 90° to a uniform magnetic field of 1.2 T. Find the magnitude of the force F on the wire.

B = 1.2 TI = 5 AL = 15 cmθ = 90°
F = N
2.Easy
B0.4 T2 A90°L = 10 cm

A straight wire 10 cm long carries 2 A at an angle of 90° to a uniform magnetic field of 0.4 T. Find the magnitude of the force F on the wire.

B = 0.4 TI = 2 AL = 10 cmθ = 90°
F = N
3.Medium
dB/dt > 0I = ?

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
  1. 1clockwise
  2. 2counterclockwise
4.Medium
vI = ?

A square loop moves to the right into a region with a uniform magnetic field pointing out of the page. Click the direction of the induced current in the loop as seen in the drawing, while the loop is entering the field.

B: out of the pageentering the field
  1. 1clockwise
  2. 2counterclockwise
5.Hard
Bn = 900 rpm15 cm × 10 cmN = 500B = 0.4 T

A coil of 500 turns, 15 cm × 10 cm, rotates at 900 rpm in a uniform field of 0.4 T about an axis perpendicular to the field. Find the peak emf E0.

N = 500A = 15 cm × 10 cmB = 0.4 Tn = 900 rpm
E0 = V
6.Hard
L = 20 mH1 → 1.5 A

The current in a 20 mH inductor changes steadily from 1 A to 1.5 A in 1 ms. Find the magnitude of the self-induced emf ε.

L = 20 mH1 A → 1.5 AΔt = 1 ms
ε = V

Answer key

  1. 1. F = 0.9 N
  2. 2. F = 0.08 N
  3. 3. counterclockwise
  4. 4. clockwise
  5. 5. E0 = 282.7 V
  6. 6. ε = 10 V

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