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 × 10⁵ m/sB = 0.01 T

A proton moves at 3 × 10⁵ m/s at an angle of 30° 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 = 3 × 10⁵ m/sB = 0.01 Tθ = 30°
F = fN
2.Easy
I = 4 AR = 8 cmB = ?N = 25

A flat circular coil of 25 turns and radius 8 cm carries a current of 4 A. Find the magnetic flux density B at its centre.

N = 25I = 4 AR = 8 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = µT
3.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
4.Medium
vI = ?

A square loop moves to the right into a region with a uniform magnetic field pointing into 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: into the pageentering the field
  1. 1clockwise
  2. 2counterclockwise
5.Hard
E = 4 × 10⁴ V/m, B1​ = 0.4 TB2​ = 0.4 Tr = ?

A deuteron passes undeflected through a velocity selector with crossed fields E = 4 × 10⁴ V/m and B₁ = 0.4 T. It then enters a second region with only a magnetic field B₂ = 0.4 T, at right angles. Find the radius r of its path there.

E = 4 × 10⁴ V/mB1 = 0.4 TB2 = 0.4 Tm = 3.344 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ C
r = cm
6.Hard
Bn = ?10 cm × 25 cmN = 500B = 0.25 T

A coil of 500 turns, 10 cm × 25 cm, rotates in a uniform field of 0.25 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 69.42 V?

N = 500A = 10 cm × 25 cmB = 0.25 TErms = 69.42 V
n = rpm

Answer key

  1. 1. F = 0.2403 fN
  2. 2. B = 785.4 µT
  3. 3. clockwise
  4. 4. counterclockwise
  5. 5. r = 0.5218 cm
  6. 6. n = 300 rpm

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