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

A straight wire 40 cm long carries 1 A at an angle of 60° to a uniform magnetic field of 0.5 T. Find the magnitude of the force F on the wire.

B = 0.5 TI = 1 AL = 40 cmθ = 60°

F = N

2.Easy

A long straight wire carries a current of 5 A. Find the magnetic flux density B at point P, 15 cm from the wire.

I = 5 Ar = 15 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

3.Medium

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

I: up the pageB: out of the page

1up the page
2to the right
3down the page
4to the left

4.Medium

An electron moving at 1 × 10⁶ m/s enters a uniform magnetic field at right angles and moves on a circle of radius 0.05686 cm. Find the magnetic flux density B.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ Cv = 1 × 10⁶ m/sr = 0.05686 cm

B = mT

5.Hard

A long air-core solenoid has 1500 turns, a length of 25 cm and a diameter of 2.5 cm. Find the energy W stored in its magnetic field when it carries 0.5 A.

N = 1500l = 25 cm⌀ = 2.5 cmI = 0.5 Aμ₀ = 4π × 10⁻⁷ T·m/A

W = µJ

6.Hard

A short coil of 20 turns is wound tightly round the middle of a long solenoid of 2000 turns, length 30 cm and diameter 3 cm. The current in the solenoid changes at 200 A/s. Find the emf ε induced in the short coil.

N₁ = 2000N₂ = 20l = 30 cm⌀ = 3 cmdi/dt = 200 A/sμ₀ = 4π × 10⁻⁷ T·m/A

ε = mV

Answer key

1. F = 0.1732 N
2. B = 6.667 µT
3. to the right
4. B = 10 mT
5. W = 694 µJ
6. ε = 23.69 mV

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