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 = 6 × 10⁵ m/sB = 0.01 T

A proton moves at 6 × 10⁵ m/s perpendicular to a uniform magnetic field of 0.01 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 6 × 10⁵ m/sB = 0.01 Tθ = 90°
F = fN
2.Easy
nB45°15 cm × 25 cmB = 0.25 T

A rectangular loop of 15 cm by 25 cm lies in a uniform magnetic field of 0.25 T. The field makes an angle of 45° with the normal of the loop. Find the magnetic flux Φ through the loop.

B = 0.25 TA = 15 cm × 25 cm45° to the normal
Φ = mWb
3.Medium
+vBF = ?

A proton moves to the left through a uniform magnetic field pointing into the page. Click the direction of the magnetic force on it.

v: to the leftB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
4.Medium
vI = ?

A square loop moves to the right into a region with a uniform magnetic field pointing out of the page. Click the direction of the induced current in the loop as seen in the drawing, while the loop is entering the field.

B: out of the pageentering the field
  1. 1clockwise
  2. 2counterclockwise
5.Hard
l = 20 cmN = 400, ⌀ 2 cm

A long air-core solenoid has 400 turns, a length of 20 cm and a diameter of 2 cm. Find its self-inductance L.

N = 400l = 20 cm⌀ = 2 cmμ₀ = 4π × 10⁻⁷ T·m/A
L = µH
6.Hard
Bn = ?12 cm × 10 cmN = 150B = 0.3 T

A coil of 150 turns, 12 cm × 10 cm, rotates in a uniform field of 0.3 T about an axis perpendicular to the field. At what speed n (in revolutions per minute) must it turn to give an rms emf of 47.98 V?

N = 150A = 12 cm × 10 cmB = 0.3 TErms = 47.98 V
n = rpm

Answer key

  1. 1. F = 0.9612 fN
  2. 2. Φ = 6.629 mWb
  3. 3. down the page
  4. 4. clockwise
  5. 5. L = 315.8 µH
  6. 6. n = 1200 rpm

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