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
B = ?I = 1 AL = 40 cmN = 400

A solenoid 40 cm long has 400 turns and carries 1 A. Find the magnetic flux density B inside it, far from the ends.

N = 400L = 40 cmI = 1 Aμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
2.Easy
+v = 1 × 10⁶ m/sB = 1 T

A proton moves at 1 × 10⁶ m/s at an angle of 60° to a uniform magnetic field of 1 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 1 × 10⁶ m/sB = 1 Tθ = 60°
F = fN
3.Medium
nBA = 80 cm², N = 250B = 0.3 T

A coil of 250 turns has an area of 80 cm². The coil sits in a uniform field of 0.3 T perpendicular to its plane, and the field is switched off in 500 ms. Find the average induced emf ε.

N = 250A = 80 cm²B = 0.3 TΔt = 500 ms
ε = V
4.Medium
IBF = ?

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

I: to the rightB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
N1​ = 800, l = 25 cm20 A/sN2​ = 100Mε = ?

A short coil of 100 turns is wound tightly round the middle of a long solenoid of 800 turns, length 25 cm and diameter 4 cm. The current in the solenoid changes at 20 A/s. Find the emf ε induced in the short coil.

N1 = 800N2 = 100l = 25 cm⌀ = 4 cmdi/dt = 20 A/sμ₀ = 4π × 10⁻⁷ T·m/A
ε = mV
6.Hard
V = 2000 VB = 0.4 Tr = ?

A proton starts from rest, is accelerated through a potential difference of 2000 V and then enters a uniform magnetic field of 0.4 T at right angles. Find the radius r of its path in the field.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 2000 VB = 0.4 T
r = cm

Answer key

  1. 1. B = 1.257 mT
  2. 2. F = 138.7 fN
  3. 3. ε = 1.2 V
  4. 4. up the page
  5. 5. ε = 10.11 mV
  6. 6. r = 1.616 cm

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