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

An alpha particle moves at 5 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.5 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 5 × 10⁶ m/sB = 0.5 Tθ = 90°

F = fN

2.Easy

A flat circular coil of 10 turns and radius 8 cm carries a current of 5 A. Find the magnetic flux density B at its centre.

N = 10I = 5 AR = 8 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

3.Medium

A coil of 20 turns has an area of 40 cm². A uniform field perpendicular to the coil rises steadily from 0 T to 0.4 T in 40 ms. Find the average induced emf ε.

N = 20A = 40 cm²B: 0 T → 0.4 TΔt = 40 ms

ε = mV

4.Medium

A metal rod 25 cm long slides at 10 m/s along two rails in a uniform field of 0.5 T into the page. The rails are joined by a resistor of 10 Ω; the rod and rails have negligible resistance. Find the power P dissipated in the resistor.

B = 0.5 TL = 25 cmv = 10 m/sR = 10 Ω

P = mW

5.Hard

A coil of 250 turns, 10 cm × 15 cm, rotates at 3000 rpm in a uniform field of 0.4 T about an axis perpendicular to the field. Find the rms value E_rms of the emf.

N = 250A = 10 cm × 15 cmB = 0.4 Tn = 3000 rpm

E_rms = V

6.Hard

A coil of 100 turns, 15 cm × 5 cm, rotates in a uniform field of 0.2 T about an axis perpendicular to the field. At what speed n (in revolutions per minute) must it turn to give an rms emf of 9.996 V?

N = 100A = 15 cm × 5 cmB = 0.2 TE_rms = 9.996 V

n = rpm

Answer key

1. F = 801 fN
2. B = 392.7 µT
3. ε = 800 mV
4. P = 156.3 mW
5. E_rms = 333.2 V
6. n = 900 rpm

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