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 = 2.5 × 10⁵ m/sB = 1.5 T

An electron moves at 2.5 × 10⁵ m/s perpendicular to a uniform magnetic field of 1.5 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 2.5 × 10⁵ m/sB = 1.5 Tθ = 90°
F = fN
2.Easy
B0.5 T1 A90°L = 40 cm

A straight wire 40 cm long carries 1 A at an angle of 90° to a uniform magnetic field of 0.5 T. Find the magnitude of the force F on the wire.

B = 0.5 TI = 1 AL = 40 cmθ = 90°
F = N
3.Medium
R = 5 Ωv = 2 m/sL = 30 cmB = 1 T

A metal rod 30 cm long slides at 2 m/s along two rails in a uniform field of 1 T into the page. Find the induced emf ε between its ends.

B = 1 TL = 30 cmv = 2 m/s
ε = mV
4.Medium
+v = 5 × 10⁵ m/sr = 4.148 cmB = ?

An alpha particle moving at 5 × 10⁵ m/s enters a uniform magnetic field at right angles and moves on a circle of radius 4.148 cm. Find the magnetic flux density B.

m = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ Cv = 5 × 10⁵ m/sr = 4.148 cm
B = T
5.Hard
V = 1000 VB = 0.5 Tr = ?

An alpha particle starts from rest, is accelerated through a potential difference of 1000 V and then enters a uniform magnetic field of 0.5 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 = 1000 VB = 0.5 T
r = cm
6.Hard
E = 8 × 10⁴ V/m, B1​ = 0.2 TB2​ = 1 Tr = ?

An alpha particle passes undeflected through a velocity selector with crossed fields E = 8 × 10⁴ V/m and B₁ = 0.2 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 = 8 × 10⁴ V/mB1 = 0.2 TB2 = 1 Tm = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ C
r = cm

Answer key

  1. 1. F = 60.07 fN
  2. 2. F = 0.2 N
  3. 3. ε = 600 mV
  4. 4. B = 0.25 T
  5. 5. r = 1.288 cm
  6. 6. r = 0.8296 cm

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