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
−v = 5 × 10⁶ m/sB = 0.1 T

An electron moves at 5 × 10⁶ m/s at an angle of 60° to a uniform magnetic field of 0.1 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 5 × 10⁶ m/sB = 0.1 Tθ = 60°
F = fN
2.Easy
B0.3 T5 A45°L = 20 cm

A straight wire 20 cm long carries 5 A at an angle of 45° to a uniform magnetic field of 0.3 T. Find the magnitude of the force F on the wire.

B = 0.3 TI = 5 AL = 20 cmθ = 45°
F = N
3.Medium
IBF = ?

A wire carries a current to the right through a uniform magnetic field pointing out of the page. Click the direction of the magnetic force on the wire.

I: to the rightB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
4.Medium
nBA = 20 cm², N = 200B = 0.5 T

A coil of 200 turns has an area of 20 cm². The coil is turned over (rotated through 180°) in a uniform field of 0.5 T, which is perpendicular to its plane, in 40 ms. Find the average induced emf ε.

N = 200A = 20 cm²B = 0.5 TΔt = 40 ms
ε = V
5.Hard
Bn = ?8 cm × 25 cmN = 250B = 0.3 T

A coil of 250 turns, 8 cm × 25 cm, rotates in a uniform field of 0.3 T about an axis perpendicular to the field. At what speed n (in revolutions per minute) must it turn to give an rms emf of 199.9 V?

N = 250A = 8 cm × 25 cmB = 0.3 TErms = 199.9 V
n = rpm
6.Hard
Bn = 600 rpm5 cm × 20 cmN = 200B = 0.3 T

A coil of 200 turns, 5 cm × 20 cm, rotates at 600 rpm in a uniform field of 0.3 T about an axis perpendicular to the field. Find the peak emf E0.

N = 200A = 5 cm × 20 cmB = 0.3 Tn = 600 rpm
E0 = V

Answer key

  1. 1. F = 69.37 fN
  2. 2. F = 0.2121 N
  3. 3. down the page
  4. 4. ε = 10 V
  5. 5. n = 1800 rpm
  6. 6. E0 = 37.7 V

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