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 = 5 × 10⁵ m/sB = 1.5 T

An alpha particle moves at 5 × 10⁵ m/s perpendicular to a uniform magnetic field of 1.5 T. Find the magnitude of the magnetic force F on it.

|q| = 3.204 × 10⁻¹⁹ Cv = 5 × 10⁵ m/sB = 1.5 Tθ = 90°
F = fN
2.Easy
B = 18.85 mTI = ?L = 15 cmN = 1500

A solenoid 15 cm long has 1500 turns. Which current I gives a magnetic flux density of 18.85 mT inside it?

N = 1500L = 15 cmB = 18.85 mTμ₀ = 4π × 10⁻⁷ T·m/A
I = A
3.Medium
IBF = ?

A wire carries a current up the page through a uniform magnetic field pointing out of the page. Click the direction of the magnetic force on the wire.

I: up the pageB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
4.Medium
R = 2.5 Ωv = 10 m/sL = 40 cmB = 1 T

A metal rod 40 cm long slides at 10 m/s along two rails in a uniform field of 1 T into the page. The rails are joined by a resistor of 2.5 Ω; the rod and rails have negligible resistance. Find the current I.

B = 1 TL = 40 cmv = 10 m/sR = 2.5 Ω
I = A
5.Hard
V = 1000 VB = 0.2 Tr = ?

A proton starts from rest, is accelerated through a potential difference of 1000 V and then enters a uniform magnetic field of 0.2 T at right angles. Find the radius r of its path in the field.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 1000 VB = 0.2 T
r = cm
6.Hard
L1​ = 100 mH100 A/sL2​ = 100 mHk = 0.5ε = ?

Two coils with self-inductances of 100 mH and 100 mH have a coupling coefficient of 0.5. The current in the first coil changes at 100 A/s. Find the emf ε induced in the second coil.

L1 = 100 mHL2 = 100 mHk = 0.5di/dt = 100 A/s
ε = V

Answer key

  1. 1. F = 240.3 fN
  2. 2. I = 1.5 A
  3. 3. to the right
  4. 4. I = 1.6 A
  5. 5. r = 2.285 cm
  6. 6. ε = 5 V

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