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 straight wire 30 cm long carries 1 A at an angle of 90° to a uniform magnetic field of 0.12 T. Find the magnitude of the force F on the wire.

B = 0.12 TI = 1 AL = 30 cmθ = 90°

F = N

2.Easy

A long straight wire carries 50 A. At what distance r from the wire is the magnetic flux density 333.3 µT?

I = 50 AB = 333.3 µTμ₀ = 4π × 10⁻⁷ T·m/A

r = cm

3.Medium

An electron moving at 4 × 10⁶ m/s enters a uniform magnetic field at right angles and moves on a circle of radius 2.274 cm. Find the magnetic flux density B.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ Cv = 4 × 10⁶ m/sr = 2.274 cm

B = mT

4.Medium

A coil of 50 turns has an area of 80 cm². The coil is turned over (rotated through 180°) in a uniform field of 0.5 T, which is perpendicular to its plane, in 500 ms. Find the average induced emf ε.

N = 50A = 80 cm²B = 0.5 TΔt = 500 ms

ε = mV

5.Hard

A deuteron passes undeflected through a velocity selector with crossed fields E = 1 × 10⁵ V/m and B₁ = 0.5 T. It then enters a second region with only a magnetic field B₂ = 0.5 T, at right angles. Find the radius r of its path there.

E = 1 × 10⁵ V/mB₁ = 0.5 TB₂ = 0.5 Tm = 3.344 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ C

r = cm

6.Hard

The current in a 200 mH inductor changes steadily from 1.5 A to 1 A in 1 ms. Find the magnitude of the self-induced emf ε.

L = 200 mH1.5 A → 1 AΔt = 1 ms

ε = V

Answer key

1. F = 0.036 N
2. r = 3 cm
3. B = 1 mT
4. ε = 800 mV
5. r = 0.835 cm
6. ε = 100 V

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