First slide

Magnetic field due to a straight current carrying wire

Question

An infinitely long straight wire is carrying current I and another wire which is parallel to the first wire , is carrying current 2I in the same direction.The wires produce a magnetic field B at the midpoint. What will be the field when 2I wire is switched off?

Easy

A

B/2
B

2B
C

B
D

4B

Solution

When two parallel conductors carrying current I and 2I in same direction, then magnetic field at the midpoint is
$B = \frac{μ_{0} 2 I}{2 πr} - \frac{μ_{0} I}{2 πr} = \frac{μ_{0} I}{2 πr}$ (Directed upwards)
When current 2I is switched off, then magnetic field due to conductor carrying current I is $B = \frac{μ_{0} I}{2 πr}$
(Directed downwards)

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App