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 25 cm long has 1200 turns and carries 1.5 A. Find the magnetic flux density B inside it, far from the ends.

N = 1200L = 25 cmI = 1.5 Aμ₀ = 4π × 10⁻⁷ T·m/A

B = mT

2.Easy

A solenoid 15 cm long has 400 turns and carries 2 A. Find the magnetic flux density B inside it, far from the ends.

N = 400L = 15 cmI = 2 Aμ₀ = 4π × 10⁻⁷ T·m/A

B = mT

3.Medium

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

B: out of the pagedB/dt > 0

1clockwise
2counterclockwise

4.Medium

An electron moves at 8 × 10⁶ m/s perpendicular to a uniform magnetic field of 4 mT. Find the radius r of its circular path.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ Cv = 8 × 10⁶ m/sB = 4 mT

r = cm

5.Hard

A long air-core solenoid has 1500 turns, a length of 40 cm and a diameter of 2 cm. Find the energy W stored in its magnetic field when it carries 2 A.

N = 1500l = 40 cm⌀ = 2 cmI = 2 Aμ₀ = 4π × 10⁻⁷ T·m/A

W = mJ

6.Hard

A long air-core solenoid has 2000 turns, a length of 20 cm and a diameter of 2.5 cm. Find its self-inductance L.

N = 2000l = 20 cm⌀ = 2.5 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = mH

Answer key

1. B = 9.048 mT
2. B = 6.702 mT
3. clockwise
4. r = 1.137 cm
5. W = 4.441 mJ
6. L = 12.34 mH

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