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
+v = 3 × 10⁶ m/sB = 0.05 T

An alpha particle moves at 3 × 10⁶ m/s perpendicular to a uniform magnetic field of 0.05 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 3 × 10⁶ m/sB = 0.05 Tθ = 90°
F = fN
2.Easy
B = 0.9425 mTI = 1.5 AL = 40 cmN = ?

A solenoid 40 cm long carries 1.5 A. How many turns N must it have for a flux density of 0.9425 mT inside?

I = 1.5 AL = 40 cmB = 0.9425 mTμ₀ = 4π × 10⁻⁷ T·m/A
N =
3.Medium
nBA = 150 cm², N = 10B: 0.2 → 0.8 T

A coil of 10 turns, area 150 cm² and resistance 8 Ω forms a closed circuit. A uniform field perpendicular to the coil rises steadily from 0.2 T to 0.8 T in 200 ms. Find the average induced current I.

N = 10A = 150 cm²B: 0.2 T → 0.8 TΔt = 200 msR = 8 Ω
I = mA
4.Medium
−vBF = ?

An electron 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
5.Hard
L1​ = 10 mH100 A/sL2​ = 200 mHk = 0.2ε = ?

Two coils with self-inductances of 10 mH and 200 mH have a coupling coefficient of 0.2. The current in the first coil changes at 100 A/s. Find the emf ε induced in the second coil.

L1 = 10 mHL2 = 200 mHk = 0.2di/dt = 100 A/s
ε = V
6.Hard
V = 2500 VB = 0.1 Tr = ?

An alpha particle starts from rest, is accelerated through a potential difference of 2500 V and then enters a uniform magnetic field of 0.1 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 = 2500 VB = 0.1 T
r = cm

Answer key

  1. 1. F = 48.06 fN
  2. 2. N = 200
  3. 3. I = 56.25 mA
  4. 4. to the right
  5. 5. ε = 0.8944 V
  6. 6. r = 10.18 cm

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