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 12 cm carries a current of 1.5 A. Find the magnetic flux density B at its centre.

N = 20I = 1.5 AR = 12 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

2.Easy

A flat circular coil of 100 turns and radius 10 cm carries a current of 2.5 A. Find the magnetic flux density B at its centre.

N = 100I = 2.5 AR = 10 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = mT

3.Medium

A proton moves to the left through a uniform magnetic field pointing into the page. Click the direction of the magnetic force on it.

v: to the leftB: into the page

1up the page
2to the right
3down the page
4to the left

4.Medium

A circular loop lies in a uniform magnetic field pointing out of the page. The field strength is decreasing. Click the direction of the induced current in the loop as seen in the drawing.

B: out of the pagedB/dt < 0

1clockwise
2counterclockwise

5.Hard

A coil of 150 turns, 12 cm × 10 cm, rotates at 1200 rpm in a uniform field of 0.05 T about an axis perpendicular to the field. Find the peak emf E₀.

N = 150A = 12 cm × 10 cmB = 0.05 Tn = 1200 rpm

E₀ = V

6.Hard

In a velocity selector, crossed fields E = 2 × 10⁴ V/m and B = 0.1 T let only ions of one speed pass straight through. Find that speed v.

E = 2 × 10⁴ V/mB₁ = 0.1 T

v = m/s

Answer key

1. B = 157.1 µT
2. B = 1.571 mT
3. down the page
4. counterclockwise
5. E₀ = 11.31 V
6. v = 200000 m/s

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