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
B0.5 TI = ?90°L = 50 cm

A straight wire 50 cm long lies at 90° to a uniform magnetic field of 0.5 T. The magnetic force on it is 1 N. Find the current I.

B = 0.5 TF = 1 NL = 50 cmθ = 90°
I = A
2.Easy
I = 4 AR = 4 cmB = ?N = 100

A flat circular coil of 100 turns and radius 4 cm carries a current of 4 A. Find the magnetic flux density B at its centre.

N = 100I = 4 AR = 4 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
+v = 5 × 10⁶ m/sr = ?B = 0.4 T

A proton moves at 5 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.4 T. Find the radius r of its circular path.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ Cv = 5 × 10⁶ m/sB = 0.4 T
r = cm
4.Medium
IBF = ?

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

I: to the leftB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
I = 4 Al = 30 cmN = 300, ⌀ 2.5 cm

A long air-core solenoid has 300 turns, a length of 30 cm and a diameter of 2.5 cm. Find the energy W stored in its magnetic field when it carries 4 A.

N = 300l = 30 cm⌀ = 2.5 cmI = 4 Aμ₀ = 4π × 10⁻⁷ T·m/A
W = mJ
6.Hard
l = 25 cmN = 800, ⌀ 1.5 cm

A long air-core solenoid has 800 turns, a length of 25 cm and a diameter of 1.5 cm. Find its self-inductance L.

N = 800l = 25 cm⌀ = 1.5 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = µH

Answer key

  1. 1. I = 4 A
  2. 2. B = 6.283 mT
  3. 3. r = 13.05 cm
  4. 4. down the page
  5. 5. W = 1.48 mJ
  6. 6. L = 568.5 µH

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