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
I = 10 APr = ?B = 200 µT

A long straight wire carries 10 A. At what distance r from the wire is the magnetic flux density 200 µT?

I = 10 AB = 200 µTμ₀ = 4π × 10⁻⁷ T·m/A
r = cm
2.Easy
B = ?I = 4 AL = 50 cmN = 500

A solenoid 50 cm long has 500 turns and carries 4 A. Find the magnetic flux density B inside it, far from the ends.

N = 500L = 50 cmI = 4 Aμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
vI = ?

A square loop moves to the right into a region with a uniform magnetic field pointing into the page. Click the direction of the induced current in the loop as seen in the drawing, while the loop is entering the field.

B: into the pageentering the field
  1. 1clockwise
  2. 2counterclockwise
4.Medium
nBA = 100 cm², N = 100B: 0 → 0.5 T

A coil of 100 turns, area 100 cm² and resistance 2 Ω forms a closed circuit. A uniform field perpendicular to the coil rises steadily from 0 T to 0.5 T in 50 ms. Find the average induced current I.

N = 100A = 100 cm²B: 0 T → 0.5 TΔt = 50 msR = 2 Ω
I = A
5.Hard
Bn = 1500 rpm10 cm × 10 cmN = 50B = 0.3 T

A coil of 50 turns, 10 cm × 10 cm, rotates at 1500 rpm in a uniform field of 0.3 T about an axis perpendicular to the field. Find the peak emf E0.

N = 50A = 10 cm × 10 cmB = 0.3 Tn = 1500 rpm
E0 = V
6.Hard
Bn = 1500 rpm20 cm × 20 cmN = 150B = 0.1 T

A coil of 150 turns, 20 cm × 20 cm, rotates at 1500 rpm in a uniform field of 0.1 T about an axis perpendicular to the field. Find the rms value Erms of the emf.

N = 150A = 20 cm × 20 cmB = 0.1 Tn = 1500 rpm
Erms = V

Answer key

  1. 1. r = 1 cm
  2. 2. B = 5.027 mT
  3. 3. counterclockwise
  4. 4. I = 5 A
  5. 5. E0 = 23.56 V
  6. 6. Erms = 66.64 V

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