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 = ?Pr = 2 cmB = 300 µT

The magnetic flux density 2 cm from a long straight wire is 300 µT. Find the current I in the wire.

B = 300 µTr = 2 cmμ₀ = 4π × 10⁻⁷ T·m/A
I = A
2.Easy
B = ?I = 2 AL = 15 cmN = 250

A solenoid 15 cm long has 250 turns and carries 2 A. Find the magnetic flux density B inside it, far from the ends.

N = 250L = 15 cmI = 2 Aμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
+vBF = ?

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

v: up the pageB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
4.Medium
2 A5 Ad = 2 cmP

Two long parallel wires 2 cm apart carry currents of 2 A and 5 A in opposite directions. Find the magnitude of the magnetic flux density B at point P, halfway between them.

I1 = 2 AI2 = 5 Ad = 2 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = µT
5.Hard
l = 30 cmN = 500, ⌀ 3 cm

A long air-core solenoid has 500 turns, a length of 30 cm and a diameter of 3 cm. Find its self-inductance L.

N = 500l = 30 cm⌀ = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = µH
6.Hard
N1​ = 800, l = 30 cmN2​ = 50M = ?

A short coil of 50 turns is wound tightly round the middle of a long solenoid of 800 turns, length 30 cm and diameter 3 cm. Find their mutual inductance M.

N1 = 800N2 = 50l = 30 cm⌀ = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
M = µH

Answer key

  1. 1. I = 30 A
  2. 2. B = 4.189 mT
  3. 3. to the right
  4. 4. B = 140 µT
  5. 5. L = 740.2 µH
  6. 6. M = 118.4 µH

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