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 = 1.5 T

A proton moves at 5 × 10⁶ m/s at an angle of 45° to a uniform magnetic field of 1.5 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 5 × 10⁶ m/sB = 1.5 Tθ = 45°
F = fN
2.Easy
B = 10.05 mTI = ?L = 10 cmN = 200

A solenoid 10 cm long has 200 turns. Which current I gives a magnetic flux density of 10.05 mT inside it?

N = 200L = 10 cmB = 10.05 mTμ₀ = 4π × 10⁻⁷ T·m/A
I = A
3.Medium
+v = 6 × 10⁶ m/sr = ?B = 0.25 T

A proton moves at 6 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.25 T. Find the radius r of its circular path.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ Cv = 6 × 10⁶ m/sB = 0.25 T
r = cm
4.Medium
8 A25 Ad = 10 cm

Two long parallel wires 10 cm apart carry currents of 8 A and 25 A in opposite directions. Find the force per metre of length F/L between them.

I1 = 8 AI2 = 25 Ad = 10 cmμ₀ = 4π × 10⁻⁷ T·m/A
F/L = µN/m
5.Hard
L = 5 mH1 → 6 A

The current in a 5 mH inductor changes steadily from 1 A to 6 A in 20 ms. Find the magnitude of the self-induced emf ε.

L = 5 mH1 A → 6 AΔt = 20 ms
ε = V
6.Hard
Bn = 900 rpm8 cm × 5 cmN = 50B = 0.05 T

A coil of 50 turns, 8 cm × 5 cm, rotates at 900 rpm in a uniform field of 0.05 T about an axis perpendicular to the field. Find the peak emf E0.

N = 50A = 8 cm × 5 cmB = 0.05 Tn = 900 rpm
E0 = V

Answer key

  1. 1. F = 849.6 fN
  2. 2. I = 3.999 A
  3. 3. r = 25.06 cm
  4. 4. F/L = 400 µN/m
  5. 5. ε = 1.25 V
  6. 6. E0 = 0.9425 V

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