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 20 A. At what distance r from the wire is the magnetic flux density 40 µT?

I = 20 AB = 40 µTμ₀ = 4π × 10⁻⁷ T·m/A

r = cm

2.Easy

A flat circular coil of 50 turns and radius 12 cm carries a current of 2.5 A. Find the magnetic flux density B at its centre.

N = 50I = 2.5 AR = 12 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

3.Medium

A coil of 200 turns has an area of 80 cm². A uniform field perpendicular to the coil rises steadily from 0.05 T to 0.25 T in 250 ms. Find the average induced emf ε.

N = 200A = 80 cm²B: 0.05 T → 0.25 TΔt = 250 ms

ε = V

4.Medium

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

B: into the pagedB/dt > 0

1clockwise
2counterclockwise

5.Hard

In a velocity selector, crossed fields E = 1 × 10⁴ V/m and B = 0.5 T let only ions of one speed pass straight through. Find that speed v.

E = 1 × 10⁴ V/mB₁ = 0.5 T

v = m/s

6.Hard

A coil of 20 turns, 20 cm × 10 cm, rotates at 3600 rpm in a uniform field of 0.1 T about an axis perpendicular to the field. Find the peak emf E₀.

N = 20A = 20 cm × 10 cmB = 0.1 Tn = 3600 rpm

E₀ = V

Answer key

1. r = 10 cm
2. B = 654.5 µT
3. ε = 1.28 V
4. counterclockwise
5. v = 20000 m/s
6. E₀ = 15.08 V

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