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
+v = 8 × 10⁶ m/sB = 0.2 T

An alpha particle moves at 8 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.2 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 8 × 10⁶ m/sB = 0.2 Tθ = 90°
F = fN
2.Easy
I = 12 APr = 5 cmB = ?

A long straight wire carries a current of 12 A. Find the magnetic flux density B at point P, 5 cm from the wire.

I = 12 Ar = 5 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = µT
3.Medium
+v = 1 × 10⁵ m/sB = 0.2 T

An alpha particle moves on a circle in a uniform magnetic field of 0.2 T. Find the time T it takes for one revolution.

m = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ CB = 0.2 T
T = ns
4.Medium
−vBF = ?

An electron moves to the left through a uniform magnetic field pointing out of the page. Click the direction of the magnetic force on it.

v: to the leftB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
l = 30 cmN = 2000, ⌀ 5 cm

A long air-core solenoid has 2000 turns, a length of 30 cm and a diameter of 5 cm. Find its self-inductance L.

N = 2000l = 30 cm⌀ = 5 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = mH
6.Hard
L = 500 mH0.5 → 3.5 A

The current in a 500 mH inductor changes steadily from 0.5 A to 3.5 A in 20 ms. Find the magnitude of the self-induced emf ε.

L = 500 mH0.5 A → 3.5 AΔt = 20 ms
ε = V

Answer key

  1. 1. F = 512.6 fN
  2. 2. B = 48 µT
  3. 3. T = 651.6 ns
  4. 4. down the page
  5. 5. L = 32.9 mH
  6. 6. ε = 75 V

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