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
nB53°5 cm × 10 cmB = 0.4 T

A rectangular loop of 5 cm by 10 cm lies in a uniform magnetic field of 0.4 T. The field lines make an angle of 37° with the plane of the loop. Find the magnetic flux Φ through the loop.

B = 0.4 TA = 5 cm × 10 cm37° to the plane
Φ = mWb
2.Easy
nB45°5 cm × 10 cmB = 0.6 T

A rectangular loop of 5 cm by 10 cm lies in a uniform magnetic field of 0.6 T. The field lines make an angle of 45° with the plane of the loop. Find the magnetic flux Φ through the loop.

B = 0.6 TA = 5 cm × 10 cm45° to the plane
Φ = mWb
3.Medium
dB/dt < 0I = ?

A circular loop lies in a uniform magnetic field pointing into the page. The field strength is decreasing. Click the direction of the induced current in the loop as seen in the drawing.

B: into the pagedB/dt < 0
  1. 1clockwise
  2. 2counterclockwise
4.Medium
IBF = ?

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

I: down the pageB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
N1​ = 1000, l = 20 cm1000 A/sN2​ = 200Mε = ?

A short coil of 200 turns is wound tightly round the middle of a long solenoid of 1000 turns, length 20 cm and diameter 3 cm. The current in the solenoid changes at 1000 A/s. Find the emf ε induced in the short coil.

N1 = 1000N2 = 200l = 20 cm⌀ = 3 cmdi/dt = 1000 A/sμ₀ = 4π × 10⁻⁷ T·m/A
ε = mV
6.Hard
l = 40 cmN = 500, ⌀ 4 cm

A long air-core solenoid has 500 turns, a length of 40 cm and a diameter of 4 cm. Find its self-inductance L.

N = 500l = 40 cm⌀ = 4 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = µH

Answer key

  1. 1. Φ = 1.204 mWb
  2. 2. Φ = 2.121 mWb
  3. 3. clockwise
  4. 4. to the right
  5. 5. ε = 888.3 mV
  6. 6. L = 987 µH

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