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 = 1.5 AL = 15 cmN = 1500

A solenoid 15 cm long has 1500 turns and carries 1.5 A. Find the magnetic flux density B inside it, far from the ends.

N = 1500L = 15 cmI = 1.5 Aμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
2.Easy
nB45°8 cm × 15 cmB = 0.6 T

A rectangular loop of 8 cm by 15 cm lies in a uniform magnetic field of 0.6 T. The field makes an angle of 45° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 0.6 TA = 8 cm × 15 cm45° to the normal
Φ = mWb
3.Medium
+vBF = ?

A proton 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
4.Medium
dB/dt < 0I = ?

A circular loop lies in a uniform magnetic field pointing into the page. The field strength is decreasing. Click the direction of the induced current in the loop as seen in the drawing.

B: into the pagedB/dt < 0
  1. 1clockwise
  2. 2counterclockwise
5.Hard
E = 1 × 10⁴ V/m, B1​ = 0.1 T

In a velocity selector, crossed fields E = 1 × 10⁴ V/m and B = 0.1 T let only ions of one speed pass straight through. Find that speed v.

E = 1 × 10⁴ V/mB1 = 0.1 T
v = m/s
6.Hard
Bn = 300 rpm20 cm × 20 cmN = 500B = 0.25 T

A coil of 500 turns, 20 cm × 20 cm, rotates at 300 rpm in a uniform field of 0.25 T about an axis perpendicular to the field. Find the peak emf E0.

N = 500A = 20 cm × 20 cmB = 0.25 Tn = 300 rpm
E0 = V

Answer key

  1. 1. B = 18.85 mT
  2. 2. Φ = 5.091 mWb
  3. 3. to the left
  4. 4. clockwise
  5. 5. v = 100000 m/s
  6. 6. E0 = 157.1 V

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