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 flat circular coil of 20 turns and radius 6 cm carries a current of 1.5 A. Find the magnetic flux density B at its centre.

N = 20I = 1.5 AR = 6 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

2.Easy

A rectangular loop of 5 cm by 15 cm lies in a uniform magnetic field of 0.4 T. The field makes an angle of 53° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 0.4 TA = 5 cm × 15 cm53° to the normal

Φ = mWb

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

A coil of 200 turns has an area of 25 cm². The coil sits in a uniform field of 0.8 T perpendicular to its plane, and the field is switched off in 500 ms. Find the average induced emf ε.

N = 200A = 25 cm²B = 0.8 TΔt = 500 ms

ε = mV

5.Hard

The current in a 25 mH inductor changes steadily from 2 A to 2.5 A in 1 ms. Find the magnitude of the self-induced emf ε.

L = 25 mH2 A → 2.5 AΔt = 1 ms

ε = V

6.Hard

The current in a 50 mH inductor changes steadily from 7 A to 2 A in 10 ms. Find the magnitude of the self-induced emf ε.

L = 50 mH7 A → 2 AΔt = 10 ms

ε = V

Answer key

1. B = 314.2 µT
2. Φ = 1.805 mWb
3. counterclockwise
4. ε = 800 mV
5. ε = 12.5 V
6. ε = 25 V

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