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

A solenoid 30 cm long carries 2.5 A. How many turns N must it have for a flux density of 2.618 mT inside?

I = 2.5 AL = 30 cmB = 2.618 mTμ₀ = 4π × 10⁻⁷ T·m/A

N =

2.Easy

A solenoid 50 cm long carries 0.5 A. How many turns N must it have for a flux density of 0.6283 mT inside?

I = 0.5 AL = 50 cmB = 0.6283 mTμ₀ = 4π × 10⁻⁷ T·m/A

N =

3.Medium

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

1clockwise
2counterclockwise

4.Medium

An alpha particle moving at 1 × 10⁶ m/s enters a uniform magnetic field at right angles and moves on a circle of radius 20.74 cm. Find the magnetic flux density B.

m = 6.645 × 10⁻²⁷ kg|q| = 3.204 × 10⁻¹⁹ Cv = 1 × 10⁶ m/sr = 20.74 cm

B = T

5.Hard

A long air-core solenoid has 2000 turns, a length of 50 cm and a diameter of 2 cm. Find the energy W stored in its magnetic field when it carries 5 A.

N = 2000l = 50 cm⌀ = 2 cmI = 5 Aμ₀ = 4π × 10⁻⁷ T·m/A

W = mJ

6.Hard

A short coil of 50 turns is wound tightly round the middle of a long solenoid of 1000 turns, length 20 cm and diameter 3 cm. Find their mutual inductance M.

N₁ = 1000N₂ = 50l = 20 cm⌀ = 3 cmμ₀ = 4π × 10⁻⁷ T·m/A

M = µH

Answer key

1. N = 250
2. N = 500
3. clockwise
4. B = 0.1 T
5. W = 39.48 mJ
6. M = 222.1 µH

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