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 100 cm long lies at 30° to a uniform magnetic field of 0.2 T. The magnetic force on it is 1.2 N. Find the current I.

B = 0.2 TF = 1.2 NL = 100 cmθ = 30°

I = A

2.Easy

A solenoid 15 cm long has 2000 turns and carries 0.5 A. Find the magnetic flux density B inside it, far from the ends.

N = 2000L = 15 cmI = 0.5 Aμ₀ = 4π × 10⁻⁷ T·m/A

B = mT

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 20 turns has an area of 40 cm². The coil is turned over (rotated through 180°) in a uniform field of 0.8 T, which is perpendicular to its plane, in 100 ms. Find the average induced emf ε.

N = 20A = 40 cm²B = 0.8 TΔt = 100 ms

ε = V

5.Hard

The current in a 50 mH inductor changes steadily from 0.5 A to 1 A in 1 ms. Find the magnitude of the self-induced emf ε.

L = 50 mH0.5 A → 1 AΔt = 1 ms

ε = V

6.Hard

A deuteron passes undeflected through a velocity selector with crossed fields E = 4 × 10⁴ V/m and B₁ = 0.4 T. It then enters a second region with only a magnetic field B₂ = 0.8 T, at right angles. Find the radius r of its path there.

E = 4 × 10⁴ V/mB₁ = 0.4 TB₂ = 0.8 Tm = 3.344 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ C

r = cm

Answer key

1. I = 12 A
2. B = 8.378 mT
3. counterclockwise
4. ε = 1.28 V
5. ε = 25 V
6. r = 0.2609 cm

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