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
nB10 cm × 25 cmB = 0.25 T

A rectangular loop of 10 cm by 25 cm lies in a uniform magnetic field of 0.25 T. The field makes an angle of 0° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 0.25 TA = 10 cm × 25 cm0° to the normal
Φ = mWb
2.Easy
I = 5 AR = 3 cmB = ?N = 10

A flat circular coil of 10 turns and radius 3 cm carries a current of 5 A. Find the magnetic flux density B at its centre.

N = 10I = 5 AR = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
vI = ?

A square loop moves to the right into a region with a uniform magnetic field pointing out of the page. Click the direction of the induced current in the loop as seen in the drawing, while the loop is entering the field.

B: out of the pageentering the field
  1. 1clockwise
  2. 2counterclockwise
4.Medium
vI = ?

A square loop moves to the right into a region with a uniform magnetic field pointing into the page. Click the direction of the induced current in the loop as seen in the drawing, while the loop is entering the field.

B: into the pageentering the field
  1. 1clockwise
  2. 2counterclockwise
5.Hard
L1​ = 80 mH100 A/sL2​ = 50 mHk = 0.2ε = ?

Two coils with self-inductances of 80 mH and 50 mH have a coupling coefficient of 0.2. The current in the first coil changes at 100 A/s. Find the emf ε induced in the second coil.

L1 = 80 mHL2 = 50 mHk = 0.2di/dt = 100 A/s
ε = V
6.Hard
E = 2 × 10⁵ V/m, B1​ = 0.05 T

In a velocity selector, crossed fields E = 2 × 10⁵ V/m and B = 0.05 T let only ions of one speed pass straight through. Find that speed v.

E = 2 × 10⁵ V/mB1 = 0.05 T
v = m/s

Answer key

  1. 1. Φ = 6.25 mWb
  2. 2. B = 1.047 mT
  3. 3. clockwise
  4. 4. counterclockwise
  5. 5. ε = 1.265 V
  6. 6. v = 4 × 10⁶ m/s

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