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 = 6 × 10⁶ m/sB = 0.02 T

An alpha particle moves at 6 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.02 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 6 × 10⁶ m/sB = 0.02 Tθ = 90°
F = fN
2.Easy
I = 2.5 AR = 3 cmB = ?N = 100

A flat circular coil of 100 turns and radius 3 cm carries a current of 2.5 A. Find the magnetic flux density B at its centre.

N = 100I = 2.5 AR = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
5 A12 Ad = 6 cmP

Two long parallel wires 6 cm apart carry currents of 5 A and 12 A in the same direction. Find the magnitude of the magnetic flux density B at point P, halfway between them.

I1 = 5 AI2 = 12 Ad = 6 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = µT
4.Medium
−vBF = ?

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

v: down the pageB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
I = 2.5 Al = 10 cmN = 1000, ⌀ 2.5 cm

A long air-core solenoid has 1000 turns, a length of 10 cm and a diameter of 2.5 cm. Find the energy W stored in its magnetic field when it carries 2.5 A.

N = 1000l = 10 cm⌀ = 2.5 cmI = 2.5 Aμ₀ = 4π × 10⁻⁷ T·m/A
W = mJ
6.Hard
E = 2 × 10⁵ V/m, B1​ = 0.25 TB2​ = 0.25 Tr = ?

A proton passes undeflected through a velocity selector with crossed fields E = 2 × 10⁵ V/m and B₁ = 0.25 T. It then enters a second region with only a magnetic field B₂ = 0.25 T, at right angles. Find the radius r of its path there.

E = 2 × 10⁵ V/mB1 = 0.25 TB2 = 0.25 Tm = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ C
r = cm

Answer key

  1. 1. F = 38.45 fN
  2. 2. B = 5.236 mT
  3. 3. B = 46.67 µT
  4. 4. to the right
  5. 5. W = 19.28 mJ
  6. 6. r = 3.342 cm

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