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 rectangular loop of 15 cm by 20 cm lies in a uniform magnetic field of 0.4 T. The field makes an angle of 60° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 0.4 TA = 15 cm × 20 cm60° to the normal

Φ = mWb

2.Easy

An electron moves at 3 × 10⁵ m/s at an angle of 45° to a uniform magnetic field of 0.1 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 3 × 10⁵ m/sB = 0.1 Tθ = 45°

F = fN

3.Medium

An electron moves at 1.5 × 10⁶ m/s perpendicular to a uniform magnetic field of 5 mT. Find the radius r of its circular path.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ Cv = 1.5 × 10⁶ m/sB = 5 mT

r = cm

4.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

5.Hard

A long air-core solenoid has 2000 turns, a length of 25 cm and a diameter of 4 cm. Find the energy W stored in its magnetic field when it carries 0.5 A.

N = 2000l = 25 cm⌀ = 4 cmI = 0.5 Aμ₀ = 4π × 10⁻⁷ T·m/A

W = mJ

6.Hard

The current in a 500 mH inductor changes steadily from 0 A to 4 A in 10 ms. Find the magnitude of the self-induced emf ε.

L = 500 mH0 A → 4 AΔt = 10 ms

ε = V

Answer key

1. Φ = 6 mWb
2. F = 3.398 fN
3. r = 0.1706 cm
4. up the page
5. W = 3.158 mJ
6. ε = 200 V

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