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 = 8 × 10⁶ m/sB = 0.05 T

An electron moves at 8 × 10⁶ m/s at an angle of 60° to a uniform magnetic field of 0.05 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 8 × 10⁶ m/sB = 0.05 Tθ = 60°
F = fN
2.Easy
B = ?I = 3 AL = 30 cmN = 500

A solenoid 30 cm long has 500 turns and carries 3 A. Find the magnetic flux density B inside it, far from the ends.

N = 500L = 30 cmI = 3 Aμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
−vBF = ?

An electron moves to the right through a uniform magnetic field pointing out of the page. Click the direction of the magnetic force on it.

v: 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
25 A15 Ad = 3 cm

Two long parallel wires 3 cm apart carry currents of 25 A and 15 A in opposite directions. Find the force per metre of length F/L between them.

I1 = 25 AI2 = 15 Ad = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
F/L = µN/m
5.Hard
Bn = 600 rpm20 cm × 10 cmN = 200B = 0.25 T

A coil of 200 turns, 20 cm × 10 cm, rotates at 600 rpm in a uniform field of 0.25 T about an axis perpendicular to the field. Find the peak emf E0.

N = 200A = 20 cm × 10 cmB = 0.25 Tn = 600 rpm
E0 = V
6.Hard
E = 1 × 10⁴ V/m, B1​ = 0.25 TB2​ = 0.25 Tr = ?

A proton passes undeflected through a velocity selector with crossed fields E = 1 × 10⁴ V/m and B₁ = 0.25 T. It then enters a second region with only a magnetic field B₂ = 0.25 T, at right angles. Find the radius r of its path there.

E = 1 × 10⁴ V/mB1 = 0.25 TB2 = 0.25 Tm = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ C
r = cm

Answer key

  1. 1. F = 55.49 fN
  2. 2. B = 6.283 mT
  3. 3. up the page
  4. 4. F/L = 2500 µN/m
  5. 5. E0 = 62.83 V
  6. 6. r = 0.1671 cm

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