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 solenoid 20 cm long has 1500 turns. Which current I gives a magnetic flux density of 28.27 mT inside it?

N = 1500L = 20 cmB = 28.27 mTμ₀ = 4π × 10⁻⁷ T·m/A

I = A

2.Easy

A proton moves at 5 × 10⁵ m/s perpendicular to a uniform magnetic field of 0.2 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 5 × 10⁵ m/sB = 0.2 Tθ = 90°

F = fN

3.Medium

A square loop moves to the right into a region with a uniform magnetic field pointing out of the page. Click the direction of the induced current in the loop as seen in the drawing, while the loop is entering the field.

B: out of the pageentering the field

1clockwise
2counterclockwise

4.Medium

An electron moves on a circle in a uniform magnetic field of 20 mT. Find the time T it takes for one revolution.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ CB = 20 mT

T = ns

5.Hard

A proton starts from rest, is accelerated through a potential difference of 5000 V and then enters a uniform magnetic field of 0.5 T at right angles. Find the radius r of its path in the field.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 5000 VB = 0.5 T

r = cm

6.Hard

A long air-core solenoid has 100 turns, a length of 40 cm and a diameter of 1.5 cm. Find its self-inductance L.

N = 100l = 40 cm⌀ = 1.5 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = µH

Answer key

1. I = 3 A
2. F = 16.02 fN
3. clockwise
4. T = 1.786 ns
5. r = 2.044 cm
6. L = 5.552 µH

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