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 = 2 × 10⁶ m/sB = 0.1 T

An alpha particle moves at 2 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.1 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 2 × 10⁶ m/sB = 0.1 Tθ = 90°
F = fN
2.Easy
I = 40 APr = 3 cmB = ?

A long straight wire carries a current of 40 A. Find the magnetic flux density B at point P, 3 cm from the wire.

I = 40 Ar = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = µT
3.Medium
−v = 2.5 × 10⁶ m/sB = 20 mT

An electron moves on a circle in a uniform magnetic field of 20 mT. Find the time T it takes for one revolution.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ CB = 20 mT
T = ns
4.Medium
−v = 8 × 10⁶ m/sr = 4.549 cmB = ?

An electron moving at 8 × 10⁶ m/s enters a uniform magnetic field at right angles and moves on a circle of radius 4.549 cm. Find the magnetic flux density B.

m = 9.109 × 10⁻³¹ kg|q| = 1.602 × 10⁻¹⁹ Cv = 8 × 10⁶ m/sr = 4.549 cm
B = mT
5.Hard
I = 1 Al = 50 cmN = 200, ⌀ 2.5 cm

A long air-core solenoid has 200 turns, a length of 50 cm and a diameter of 2.5 cm. Find the energy W stored in its magnetic field when it carries 1 A.

N = 200l = 50 cm⌀ = 2.5 cmI = 1 Aμ₀ = 4π × 10⁻⁷ T·m/A
W = µJ
6.Hard
V = 2500 VB = 0.25 Tr = ?

A deuteron starts from rest, is accelerated through a potential difference of 2500 V and then enters a uniform magnetic field of 0.25 T at right angles. Find the radius r of its path in the field.

m = 3.344 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 2500 VB = 0.25 T
r = cm

Answer key

  1. 1. F = 64.08 fN
  2. 2. B = 266.7 µT
  3. 3. T = 1.786 ns
  4. 4. B = 1 mT
  5. 5. W = 24.67 µJ
  6. 6. r = 4.086 cm

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