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.

New worksheet Practise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________ Date: ____________

1.Easy

A long straight wire carries a current of 40 A. Find the magnetic flux density B at point P, 15 cm from the wire.

I = 40 Ar = 15 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

2.Easy

A straight wire 15 cm long lies at 45° to a uniform magnetic field of 0.08 T. The magnetic force on it is 0.1697 N. Find the current I.

B = 0.08 TF = 0.1697 NL = 15 cmθ = 45°

I = A

3.Medium

A square loop moves to the right into a region with a uniform magnetic field pointing into 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: into the pageentering the field

1clockwise
2counterclockwise

4.Medium

Two long parallel wires 6 cm apart carry currents of 20 A and 15 A in the same direction. Find the force per metre of length F/L between them.

I₁ = 20 AI₂ = 15 Ad = 6 cmμ₀ = 4π × 10⁻⁷ T·m/A

F/L = µN/m

5.Hard

A long air-core solenoid has 300 turns, a length of 40 cm and a diameter of 1 cm. Find the energy W stored in its magnetic field when it carries 1.5 A.

N = 300l = 40 cm⌀ = 1 cmI = 1.5 Aμ₀ = 4π × 10⁻⁷ T·m/A

W = µJ

6.Hard

A short coil of 100 turns is wound tightly round the middle of a long solenoid of 500 turns, length 20 cm and diameter 5 cm. The current in the solenoid changes at 1000 A/s. Find the emf ε induced in the short coil.

N₁ = 500N₂ = 100l = 20 cm⌀ = 5 cmdi/dt = 1000 A/sμ₀ = 4π × 10⁻⁷ T·m/A

ε = mV

Answer key

1. B = 53.33 µT
2. I = 20 A
3. counterclockwise
4. F/L = 1000 µN/m
5. W = 24.98 µJ
6. ε = 616.9 mV

Full step-by-step solutions: practise this topic on examproblems.com.