Question

An unusual lightning strike has a vertical portion with a current of –400 A downwards. The Earth’s magnetic field at that location is parallel to the ground and has a magnitude of 30 μT. In units of N (Newtons), the force exerted by the Earth’s magnetic field on the 25 m-long current is

Answer 1

Answer:

The magnetic force is 0.3 N.        

Explanation:

Given that,

Current in an unusual lightning strike, I = -400 A

The Earth’s magnetic field at that location is parallel to the ground and has a magnitude of 30 μT, $B=30\times 10^{-6}\ T$

We need to find the force exerted by the Earth’s magnetic field on the 25 m-long current.

The magnetic force is given by :

$F=ILB\\\\F=400\times 25\times 30\times 10^{-6}\\\\F=0.3\ N$

So, the magnetic force is 0.3 N.