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
I = 4 APr = 1 cmB = ?

A long straight wire carries a current of 4 A. Find the magnetic flux density B at point P, 1 cm from the wire.

I = 4 Ar = 1 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = µT
2.Easy
B = ?I = 5 AL = 50 cmN = 500

A solenoid 50 cm long has 500 turns and carries 5 A. Find the magnetic flux density B inside it, far from the ends.

N = 500L = 50 cmI = 5 Aμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
R = 10 Ωv = 1 m/sL = 100 cmB = 0.8 T

A metal rod 100 cm long slides at 1 m/s along two rails in a uniform field of 0.8 T into the page. Find the induced emf ε between its ends.

B = 0.8 TL = 100 cmv = 1 m/s
ε = mV
4.Medium
nBA = 10 cm², N = 500B = 0.1 T

A coil of 500 turns has an area of 10 cm². The coil sits in a uniform field of 0.1 T perpendicular to its plane, and the field is switched off in 100 ms. Find the average induced emf ε.

N = 500A = 10 cm²B = 0.1 TΔt = 100 ms
ε = mV
5.Hard
V = 2500 VB = 0.5 Tr = ?

A deuteron starts from rest, is accelerated through a potential difference of 2500 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 = 3.344 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 2500 VB = 0.5 T
r = cm
6.Hard
V = 2000 VB = 0.3 Tr = ?

An alpha particle starts from rest, is accelerated through a potential difference of 2000 V and then enters a uniform magnetic field of 0.3 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 = 2000 VB = 0.3 T
r = cm

Answer key

  1. 1. B = 80 µT
  2. 2. B = 6.283 mT
  3. 3. ε = 800 mV
  4. 4. ε = 500 mV
  5. 5. r = 2.043 cm
  6. 6. r = 3.036 cm

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