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 long straight wire carries 30 A. At what distance r from the wire is the magnetic flux density 600 µT?

I = 30 AB = 600 µTμ₀ = 4π × 10⁻⁷ T·m/A

r = cm

2.Easy

A long straight wire carries 25 A. At what distance r from the wire is the magnetic flux density 125 µT?

I = 25 AB = 125 µTμ₀ = 4π × 10⁻⁷ T·m/A

r = cm

3.Medium

A proton moves on a circle in a uniform magnetic field of 0.5 T. Find the time T it takes for one revolution.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CB = 0.5 T

T = ns

4.Medium

A square loop moves to the right into a region with a uniform magnetic field pointing out of 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: out of the pageentering the field

1clockwise
2counterclockwise

5.Hard

Two coils with self-inductances of 20 mH and 200 mH have a coupling coefficient of 0.4. The current in the first coil changes at 50 A/s. Find the emf ε induced in the second coil.

L₁ = 20 mHL₂ = 200 mHk = 0.4di/dt = 50 A/s

ε = V

6.Hard

A proton starts from rest, is accelerated through a potential difference of 500 V and then enters a uniform magnetic field of 0.5 T at right angles. Find the radius r of its path in the field.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 500 VB = 0.5 T

r = cm

Answer key

1. r = 1 cm
2. r = 4 cm
3. T = 131.2 ns
4. clockwise
5. ε = 1.265 V
6. r = 0.6463 cm

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