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
B0.4 TI = ?30°L = 80 cm

A straight wire 80 cm long lies at 30° to a uniform magnetic field of 0.4 T. The magnetic force on it is 0.48 N. Find the current I.

B = 0.4 TF = 0.48 NL = 80 cmθ = 30°
I = A
2.Easy
B0.25 TI = ?30°L = 20 cm

A straight wire 20 cm long lies at 30° to a uniform magnetic field of 0.25 T. The magnetic force on it is 0.2 N. Find the current I.

B = 0.25 TF = 0.2 NL = 20 cmθ = 30°
I = A
3.Medium
nBA = 10 cm², N = 200B: 0.05 → 0.25 T

A coil of 200 turns, area 10 cm² and resistance 5 Ω forms a closed circuit. A uniform field perpendicular to the coil rises steadily from 0.05 T to 0.25 T in 50 ms. Find the average induced current I.

N = 200A = 10 cm²B: 0.05 T → 0.25 TΔt = 50 msR = 5 Ω
I = mA
4.Medium
IBF = ?

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

I: to the leftB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
I = 0.5 Al = 25 cmN = 2000, ⌀ 3 cm

A long air-core solenoid has 2000 turns, a length of 25 cm and a diameter of 3 cm. Find the energy W stored in its magnetic field when it carries 0.5 A.

N = 2000l = 25 cm⌀ = 3 cmI = 0.5 Aμ₀ = 4π × 10⁻⁷ T·m/A
W = mJ
6.Hard
E = 2 × 10⁴ V/m, B1​ = 0.25 TB2​ = 1 Tr = ?

A proton passes undeflected through a velocity selector with crossed fields E = 2 × 10⁴ V/m and B₁ = 0.25 T. It then enters a second region with only a magnetic field B₂ = 1 T, at right angles. Find the radius r of its path there.

E = 2 × 10⁴ V/mB1 = 0.25 TB2 = 1 Tm = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ C
r = cm

Answer key

  1. 1. I = 3 A
  2. 2. I = 8 A
  3. 3. I = 160 mA
  4. 4. down the page
  5. 5. W = 1.777 mJ
  6. 6. r = 0.08355 cm

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