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 straight wire 15 cm long lies at 60° to a uniform magnetic field of 0.12 T. The magnetic force on it is 0.1247 N. Find the current I.

B = 0.12 TF = 0.1247 NL = 15 cmθ = 60°

I = A

2.Easy

An alpha particle moves at 4 × 10⁵ m/s at an angle of 60° to a uniform magnetic field of 1 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 4 × 10⁵ m/sB = 1 Tθ = 60°

F = fN

3.Medium

Two long parallel wires 20 cm apart carry currents of 10 A and 2 A in the same direction. Find the force per metre of length F/L between them.

I₁ = 10 AI₂ = 2 Ad = 20 cmμ₀ = 4π × 10⁻⁷ T·m/A

F/L = µN/m

4.Medium

A coil of 250 turns has an area of 10 cm². The coil sits in a uniform field of 0.2 T perpendicular to its plane, and the field is switched off in 200 ms. Find the average induced emf ε.

N = 250A = 10 cm²B = 0.2 TΔt = 200 ms

ε = mV

5.Hard

A long air-core solenoid has 500 turns, a length of 50 cm and a diameter of 1 cm. Find the energy W stored in its magnetic field when it carries 0.5 A.

N = 500l = 50 cm⌀ = 1 cmI = 0.5 Aμ₀ = 4π × 10⁻⁷ T·m/A

W = µJ

6.Hard

An alpha particle starts from rest, is accelerated through a potential difference of 1000 V and then enters a uniform magnetic field of 0.2 T at right angles. Find the radius r of its path in the field.

m = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ CV = 1000 VB = 0.2 T

r = cm

Answer key

1. I = 8 A
2. F = 111 fN
3. F/L = 20 µN/m
4. ε = 250 mV
5. W = 6.169 µJ
6. r = 3.22 cm

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