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 = 6.702 mTI = 4 AL = 15 cmN = ?

A solenoid 15 cm long carries 4 A. How many turns N must it have for a flux density of 6.702 mT inside?

I = 4 AL = 15 cmB = 6.702 mTμ₀ = 4π × 10⁻⁷ T·m/A
N =
2.Easy
−v = 6 × 10⁵ m/sB = 0.05 T

An electron moves at 6 × 10⁵ 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 = 6 × 10⁵ m/sB = 0.05 Tθ = 60°
F = fN
3.Medium
nBA = 25 cm², N = 25B: 0 → 0.4 T

A coil of 25 turns, area 25 cm² and resistance 10 Ω forms a closed circuit. A uniform field perpendicular to the coil rises steadily from 0 T to 0.4 T in 20 ms. Find the average induced current I.

N = 25A = 25 cm²B: 0 T → 0.4 TΔt = 20 msR = 10 Ω
I = mA
4.Medium
IBF = ?

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

I: to the rightB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
Bn = 900 rpm12 cm × 25 cmN = 250B = 0.25 T

A coil of 250 turns, 12 cm × 25 cm, rotates at 900 rpm in a uniform field of 0.25 T about an axis perpendicular to the field. Find the peak emf E0.

N = 250A = 12 cm × 25 cmB = 0.25 Tn = 900 rpm
E0 = V
6.Hard
Bn = 3600 rpm20 cm × 10 cmN = 250B = 0.1 T

A coil of 250 turns, 20 cm × 10 cm, rotates at 3600 rpm in a uniform field of 0.1 T about an axis perpendicular to the field. Find the peak emf E0.

N = 250A = 20 cm × 10 cmB = 0.1 Tn = 3600 rpm
E0 = V

Answer key

  1. 1. N = 200
  2. 2. F = 4.162 fN
  3. 3. I = 125 mA
  4. 4. up the page
  5. 5. E0 = 176.7 V
  6. 6. E0 = 188.5 V

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