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 single circular loop of wire with radius 6 cm carries a current of 0.5 A. Find the magnetic flux density B at its centre.

N = 1I = 0.5 AR = 6 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

2.Easy

A solenoid 10 cm long has 2000 turns and carries 4 A. Find the magnetic flux density B inside it, far from the ends.

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

B = mT

3.Medium

Two long parallel wires 12 cm apart carry currents of 15 A and 15 A in opposite directions. Find the magnitude of the magnetic flux density B at point P, halfway between them.

I₁ = 15 AI₂ = 15 Ad = 12 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

4.Medium

A wire carries a current down the page through a uniform magnetic field pointing into the page. Click the direction of the magnetic force on the wire.

I: down the pageB: into the page

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

5.Hard

A long air-core solenoid has 800 turns, a length of 10 cm and a diameter of 3 cm. Find its self-inductance L.

N = 800l = 10 cm⌀ = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = mH

6.Hard

A coil of 50 turns, 15 cm × 10 cm, rotates at 900 rpm in a uniform field of 0.3 T about an axis perpendicular to the field. Find the peak emf E₀.

N = 50A = 15 cm × 10 cmB = 0.3 Tn = 900 rpm

E₀ = V

Answer key

1. B = 5.236 µT
2. B = 100.5 mT
3. B = 100 µT
4. to the right
5. L = 5.685 mH
6. E₀ = 21.21 V

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