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
B = 22.62 mTI = ?L = 10 cmN = 1200

A solenoid 10 cm long has 1200 turns. Which current I gives a magnetic flux density of 22.62 mT inside it?

N = 1200L = 10 cmB = 22.62 mTμ₀ = 4π × 10⁻⁷ T·m/A
I = A
2.Easy
I = 4 AR = 4 cmB = ?N = 100

A flat circular coil of 100 turns and radius 4 cm carries a current of 4 A. Find the magnetic flux density B at its centre.

N = 100I = 4 AR = 4 cmμ₀ = 4π × 10⁻⁷ T·m/A
B = mT
3.Medium
−vBF = ?

An electron moves up the page through a uniform magnetic field pointing into the page. Click the direction of the magnetic force on it.

v: up the pageB: into the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
4.Medium
−vBF = ?

An electron moves to the right through a uniform magnetic field pointing out of the page. Click the direction of the magnetic force on it.

v: to the rightB: out of the page
  1. 1up the page
  2. 2to the right
  3. 3down the page
  4. 4to the left
5.Hard
V = 5000 VB = 0.25 Tr = ?

A proton starts from rest, is accelerated through a potential difference of 5000 V and then enters a uniform magnetic field of 0.25 T at right angles. Find the radius r of its path in the field.

m = 1.673 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ CV = 5000 VB = 0.25 T
r = cm
6.Hard
E = 8 × 10⁴ V/m, B1​ = 0.4 T

In a velocity selector, crossed fields E = 8 × 10⁴ V/m and B = 0.4 T let only ions of one speed pass straight through. Find that speed v.

E = 8 × 10⁴ V/mB1 = 0.4 T
v = m/s

Answer key

  1. 1. I = 1.5 A
  2. 2. B = 6.283 mT
  3. 3. to the right
  4. 4. up the page
  5. 5. r = 4.088 cm
  6. 6. v = 200000 m/s

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