Question

15) An electric current passes through a long straight copper wire. At a distance 5 cm from
the straight wire, the magnetic field is B. The magnetic field at 20 cm from the straight
wire would b​

Answer 1

Answer:

1/4

Explanation:

By Ampere's circuit law, we have B(2πr)=μ

0

I.

In this scenario, I is the enclosed current and it remains same. Only, the radius is increased 4 times.

So, the magnetic field becomes one-fourth.