Question

A force of 1.5 × 102 N is exerted on a charge of 1.4 × 10–7 C that is traveling at an angle of 75° to a magnetic field.

If the charge is moving at 1.3 × 106 m/s, what is the magnetic field strength?

8.2 × 102 T
8.5 × 102 T
3.2 × 103 T
6.4 × 1010 T

Answer 1

Use F = q v B sinθ, so B = F / (q v sinθ).

sin75° ≈ 0.966. Thus
B = 1.5×10^2 / (1.4×10^−7 × 1.3×10^6 × 0.966)
≈ 150 / 0.176 ≈ 8.5×10^2 T.

Answer: 8.5 × 10^2 T.