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

I = 40 AB = 40 µTμ₀ = 4π × 10⁻⁷ T·m/A

r = cm

2.Easy

The magnetic flux density 3 cm from a long straight wire is 33.33 µT. Find the current I in the wire.

B = 33.33 µTr = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A

I = A

3.Medium

A proton moves at 1.5 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.5 T. Find the radius r of its circular path.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ Cv = 1.5 × 10⁶ m/sB = 0.5 T

r = cm

4.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

5.Hard

A coil of 50 turns, 5 cm × 10 cm, rotates at 3600 rpm in a uniform field of 0.25 T about an axis perpendicular to the field. Find the peak emf E₀.

N = 50A = 5 cm × 10 cmB = 0.25 Tn = 3600 rpm

E₀ = V

6.Hard

A proton starts from rest, is accelerated through a potential difference of 5000 V and then enters a uniform magnetic field of 0.8 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 = 5000 VB = 0.8 T

r = cm

Answer key

1. r = 20 cm
2. I = 4.999 A
3. r = 3.133 cm
4. counterclockwise
5. E₀ = 23.56 V
6. r = 1.277 cm

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