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

An alpha particle moves at 1.5 × 10⁵ m/s at an angle of 45° to a uniform magnetic field of 1 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 1.5 × 10⁵ m/sB = 1 Tθ = 45°

F = fN

2.Easy

A long straight wire carries a current of 2 A. Find the magnetic flux density B at point P, 3 cm from the wire.

I = 2 Ar = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

3.Medium

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

v: to the leftB: into the page

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

4.Medium

Two long parallel wires 15 cm apart carry currents of 2 A and 12 A in opposite directions. Find the force per metre of length F/L between them.

I₁ = 2 AI₂ = 12 Ad = 15 cmμ₀ = 4π × 10⁻⁷ T·m/A

F/L = µN/m

5.Hard

A long air-core solenoid has 1000 turns, a length of 20 cm and a diameter of 1 cm. Find the energy W stored in its magnetic field when it carries 5 A.

N = 1000l = 20 cm⌀ = 1 cmI = 5 Aμ₀ = 4π × 10⁻⁷ T·m/A

W = mJ

6.Hard

A coil of 200 turns, 15 cm × 25 cm, rotates at 3600 rpm in a uniform field of 0.5 T about an axis perpendicular to the field. Find the peak emf E₀.

N = 200A = 15 cm × 25 cmB = 0.5 Tn = 3600 rpm

E₀ = V

Answer key

1. F = 33.98 fN
2. B = 13.33 µT
3. up the page
4. F/L = 32 µN/m
5. W = 6.169 mJ
6. E₀ = 1414 V

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