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
nB30°20 cm × 15 cmB = 1.2 T

A rectangular loop of 20 cm by 15 cm lies in a uniform magnetic field of 1.2 T. The field makes an angle of 30° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 1.2 TA = 20 cm × 15 cm30° to the normal
Φ = mWb
2.Easy
I = 4 APr = 8 cmB = ?

A long straight wire carries a current of 4 A. Find the magnetic flux density B at point P, 8 cm from the wire.

I = 4 Ar = 8 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = µT
3.Medium
R = 10 Ωv = 6 m/sL = 50 cmB = 0.2 T

A metal rod 50 cm long slides at 6 m/s along two rails in a uniform field of 0.2 T into the page. The rails are joined by a resistor of 10 Ω; the rod and rails have negligible resistance. Find the power P dissipated in the resistor.

B = 0.2 TL = 50 cmv = 6 m/sR = 10 Ω
P = mW
4.Medium
−vBF = ?

An electron moves to the left through a uniform magnetic field pointing out of the page. Click the direction of the magnetic force on it.

v: to the leftB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
L = 5 mH5.5 → 0.5 A

The current in a 5 mH inductor changes steadily from 5.5 A to 0.5 A in 1 ms. Find the magnitude of the self-induced emf ε.

L = 5 mH5.5 A → 0.5 AΔt = 1 ms
ε = V
6.Hard
I = 4 Al = 30 cmN = 1500, ⌀ 2.5 cm

A long air-core solenoid has 1500 turns, a length of 30 cm and a diameter of 2.5 cm. Find the energy W stored in its magnetic field when it carries 4 A.

N = 1500l = 30 cm⌀ = 2.5 cmI = 4 Aμ₀ = 4π × 10⁻⁷ T·m/A
W = mJ

Answer key

  1. 1. Φ = 31.18 mWb
  2. 2. B = 10 µT
  3. 3. P = 36 mW
  4. 4. down the page
  5. 5. ε = 25 V
  6. 6. W = 37.01 mJ

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