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
I = 3 AR = 3 cmB = ?N = 50

A flat circular coil of 50 turns and radius 3 cm carries a current of 3 A. Find the magnetic flux density B at its centre.

N = 50I = 3 AR = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
2.Easy
I = 2.5 AR = 3 cmB = ?N = 50

A flat circular coil of 50 turns and radius 3 cm carries a current of 2.5 A. Find the magnetic flux density B at its centre.

N = 50I = 2.5 AR = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
IBF = ?

A wire carries a current to the left through a uniform magnetic field pointing out of the page. Click the direction of the magnetic force on the wire.

I: to the leftB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
4.Medium
+vBF = ?

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

v: to the rightB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
L = 50 mH2 → 3.5 A

The current in a 50 mH inductor changes steadily from 2 A to 3.5 A in 2 ms. Find the magnitude of the self-induced emf ε.

L = 50 mH2 A → 3.5 AΔt = 2 ms
ε = V
6.Hard
l = 50 cmN = 2000, ⌀ 1.5 cm

A long air-core solenoid has 2000 turns, a length of 50 cm and a diameter of 1.5 cm. Find its self-inductance L.

N = 2000l = 50 cm⌀ = 1.5 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = mH

Answer key

  1. 1. B = 3.142 mT
  2. 2. B = 2.618 mT
  3. 3. up the page
  4. 4. down the page
  5. 5. ε = 37.5 V
  6. 6. L = 1.777 mH

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