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 = ?Pr = 2 cmB = 120 µT

The magnetic flux density 2 cm from a long straight wire is 120 µT. Find the current I in the wire.

B = 120 µTr = 2 cmμ₀ = 4π × 10⁻⁷ T·m/A
I = A
2.Easy
B0.1 TI = ?60°L = 80 cm

A straight wire 80 cm long lies at 60° to a uniform magnetic field of 0.1 T. The magnetic force on it is 0.2771 N. Find the current I.

B = 0.1 TF = 0.2771 NL = 80 cmθ = 60°
I = A
3.Medium
nBA = 25 cm², N = 250B: 0.2 → 0.8 T

A coil of 250 turns has an area of 25 cm². A uniform field perpendicular to the coil rises steadily from 0.2 T to 0.8 T in 40 ms. Find the average induced emf ε.

N = 250A = 25 cm²B: 0.2 T → 0.8 TΔt = 40 ms
ε = V
4.Medium
−vBF = ?

An electron moves up the page through a uniform magnetic field pointing into the page. Click the direction of the magnetic force on it.

v: up the pageB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
l = 10 cmN = 500, ⌀ 3 cm

A long air-core solenoid has 500 turns, a length of 10 cm and a diameter of 3 cm. Find its self-inductance L.

N = 500l = 10 cm⌀ = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = mH
6.Hard
l = 30 cmN = 800, ⌀ 5 cm

A long air-core solenoid has 800 turns, a length of 30 cm and a diameter of 5 cm. Find its self-inductance L.

N = 800l = 30 cm⌀ = 5 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = mH

Answer key

  1. 1. I = 12 A
  2. 2. I = 4 A
  3. 3. ε = 9.375 V
  4. 4. to the right
  5. 5. L = 2.221 mH
  6. 6. L = 5.264 mH

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