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.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
B0.3 TI = ?30°L = 10 cm

A straight wire 10 cm long lies at 30° to a uniform magnetic field of 0.3 T. The magnetic force on it is 0.075 N. Find the current I.

B = 0.3 TF = 0.075 NL = 10 cmθ = 30°
I = A
2.Easy
B = 25.13 mTI = ?L = 25 cmN = 1000

A solenoid 25 cm long has 1000 turns. Which current I gives a magnetic flux density of 25.13 mT inside it?

N = 1000L = 25 cmB = 25.13 mTμ₀ = 4π × 10⁻⁷ T·m/A
I = A
3.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
4.Medium
dB/dt < 0I = ?

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

B: out of the pagedB/dt < 0
  1. 1clockwise
  2. 2counterclockwise
5.Hard
l = 15 cmN = 2000, ⌀ 2 cm

A long air-core solenoid has 2000 turns, a length of 15 cm and a diameter of 2 cm. Find its self-inductance L.

N = 2000l = 15 cm⌀ = 2 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = mH
6.Hard
L = 100 mH0.5 → 1 A

The current in a 100 mH inductor changes steadily from 0.5 A to 1 A in 50 ms. Find the magnitude of the self-induced emf ε.

L = 100 mH0.5 A → 1 AΔt = 50 ms
ε = V

Answer key

  1. 1. I = 5 A
  2. 2. I = 4.999 A
  3. 3. clockwise
  4. 4. counterclockwise
  5. 5. L = 10.53 mH
  6. 6. ε = 1 V

Full step-by-step solutions: practise this topic on examproblems.com.