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 10 cm long has 1500 turns. Which current I gives a magnetic flux density of 56.55 mT inside it?

N = 1500L = 10 cmB = 56.55 mTμ₀ = 4π × 10⁻⁷ T·m/A

I = A

2.Easy

A solenoid 20 cm long has 2000 turns. Which current I gives a magnetic flux density of 25.13 mT inside it?

N = 2000L = 20 cmB = 25.13 mTμ₀ = 4π × 10⁻⁷ T·m/A

I = A

3.Medium

A proton moving at 2.5 × 10⁶ m/s enters a uniform magnetic field at right angles and moves on a circle of radius 1.741 cm. Find the magnetic flux density B.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ Cv = 2.5 × 10⁶ m/sr = 1.741 cm

B = T

4.Medium

A coil of 10 turns has an area of 200 cm². The coil sits in a uniform field of 0.5 T perpendicular to its plane, and the field is switched off in 100 ms. Find the average induced emf ε.

N = 10A = 200 cm²B = 0.5 TΔt = 100 ms

ε = V

5.Hard

A coil of 150 turns, 10 cm × 25 cm, rotates in a uniform field of 0.1 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 41.65 V?

N = 150A = 10 cm × 25 cmB = 0.1 TE_rms = 41.65 V

n = rpm

6.Hard

A deuteron starts from rest, is accelerated through a potential difference of 1000 V and then enters a uniform magnetic field of 0.8 T at right angles. Find the radius r of its path in the field.

m = 3.344 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 1000 VB = 0.8 T

r = cm

Answer key

1. I = 3 A
2. I = 2 A
3. B = 1.5 T
4. ε = 1 V
5. n = 1500 rpm
6. r = 0.8077 cm

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