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
nB8 cm × 30 cmB = 0.3 T

A rectangular loop of 8 cm by 30 cm lies in a uniform magnetic field of 0.3 T. The field makes an angle of 0° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 0.3 TA = 8 cm × 30 cm0° to the normal
Φ = mWb
2.Easy
I = 1.5 AR = 3 cmB = ?N = 100

A flat circular coil of 100 turns and radius 3 cm carries a current of 1.5 A. Find the magnetic flux density B at its centre.

N = 100I = 1.5 AR = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
IBF = ?

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

I: to the rightB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
4.Medium
nBA = 100 cm², N = 10B: 0 → 0.5 T

A coil of 10 turns, area 100 cm² and resistance 25 Ω forms a closed circuit. A uniform field perpendicular to the coil rises steadily from 0 T to 0.5 T in 500 ms. Find the average induced current I.

N = 10A = 100 cm²B: 0 T → 0.5 TΔt = 500 msR = 25 Ω
I = mA
5.Hard
V = 10000 VB = 0.8 Tr = ?

An alpha particle starts from rest, is accelerated through a potential difference of 10000 V and then enters a uniform magnetic field of 0.8 T at right angles. Find the radius r of its path in the field.

m = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ CV = 10000 VB = 0.8 T
r = cm
6.Hard
I = 0.5 Al = 30 cmN = 500, ⌀ 1.5 cm

A long air-core solenoid has 500 turns, a length of 30 cm and a diameter of 1.5 cm. Find the energy W stored in its magnetic field when it carries 0.5 A.

N = 500l = 30 cm⌀ = 1.5 cmI = 0.5 Aμ₀ = 4π × 10⁻⁷ T·m/A
W = µJ

Answer key

  1. 1. Φ = 7.2 mWb
  2. 2. B = 3.142 mT
  3. 3. up the page
  4. 4. I = 4 mA
  5. 5. r = 2.546 cm
  6. 6. W = 23.13 µJ

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