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 = 1 AR = 2 cmB = ?N = 100

A flat circular coil of 100 turns and radius 2 cm carries a current of 1 A. Find the magnetic flux density B at its centre.

N = 100I = 1 AR = 2 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
2.Easy
I = 0.5 AR = 4 cmB = ?

A single circular loop of wire with radius 4 cm carries a current of 0.5 A. Find the magnetic flux density B at its centre.

N = 1I = 0.5 AR = 4 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = µT
3.Medium
IBF = ?

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

I: to the rightB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
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​ = 10 mH100 A/sL2​ = 10 mHk = 0.3ε = ?

Two coils with self-inductances of 10 mH and 10 mH have a coupling coefficient of 0.3. The current in the first coil changes at 100 A/s. Find the emf ε induced in the second coil.

L1 = 10 mHL2 = 10 mHk = 0.3di/dt = 100 A/s
ε = V
6.Hard
E = 1 × 10⁴ V/m, B1​ = 0.2 T

In a velocity selector, crossed fields E = 1 × 10⁴ V/m and B = 0.2 T let only ions of one speed pass straight through. Find that speed v.

E = 1 × 10⁴ V/mB1 = 0.2 T
v = m/s

Answer key

  1. 1. B = 3.142 mT
  2. 2. B = 7.854 µT
  3. 3. down the page
  4. 4. counterclockwise
  5. 5. ε = 0.3 V
  6. 6. v = 50000 m/s

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