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
B = 6.283 mTI = ?L = 12 cmN = 600

A solenoid 12 cm long has 600 turns. Which current I gives a magnetic flux density of 6.283 mT inside it?

N = 600L = 12 cmB = 6.283 mTμ₀ = 4π × 10⁻⁷ T·m/A
I = A
2.Easy
B0.8 T15 A45°L = 25 cm

A straight wire 25 cm long carries 15 A at an angle of 45° to a uniform magnetic field of 0.8 T. Find the magnitude of the force F on the wire.

B = 0.8 TI = 15 AL = 25 cmθ = 45°
F = N
3.Medium
+v = 6 × 10⁶ m/sB = 0.2 T

A proton moves on a circle in a uniform magnetic field of 0.2 T. Find the time T it takes for one revolution.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CB = 0.2 T
T = ns
4.Medium
−v = 2 × 10⁶ m/sr = ?B = 4 mT

An electron moves at 2 × 10⁶ m/s perpendicular to a uniform magnetic field of 4 mT. Find the radius r of its circular path.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ Cv = 2 × 10⁶ m/sB = 4 mT
r = cm
5.Hard
Bn = 900 rpm12 cm × 10 cmN = 250B = 0.3 T

A coil of 250 turns, 12 cm × 10 cm, rotates at 900 rpm in a uniform field of 0.3 T about an axis perpendicular to the field. Find the rms value Erms of the emf.

N = 250A = 12 cm × 10 cmB = 0.3 Tn = 900 rpm
Erms = V
6.Hard
Bn = 3600 rpm5 cm × 25 cmN = 20B = 0.3 T

A coil of 20 turns, 5 cm × 25 cm, rotates at 3600 rpm in a uniform field of 0.3 T about an axis perpendicular to the field. Find the peak emf E0.

N = 20A = 5 cm × 25 cmB = 0.3 Tn = 3600 rpm
E0 = V

Answer key

  1. 1. I = 1 A
  2. 2. F = 2.121 N
  3. 3. T = 328.1 ns
  4. 4. r = 0.2843 cm
  5. 5. Erms = 59.98 V
  6. 6. E0 = 28.27 V

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