IIT JEE Physics (1978-2018: 41 Years) Topic-wise Complete Solutions

# Attraction and Repulsion between Current Carrying Conductors

## Introduction

When two parallel wires are placed close to each other then they attract each other if direction of current is parallel and repel each other if direction of current is anti-parallel. This can be explained by seeing the force on a current carrying wire placed in the magnetic field of the other wire.

## Apparatus

two coils, battery

## Procedure

Make two coils (radius 2 cm, number of turns 100). Hang these coils with their planes parallel to each other. Connect both coils to a battery/power supply. See attraction/repulsion between them by changing direction of current.

## Discussion

This demonstration is to show attraction and repulsion between current carrying conductors. A current carrying coil acts as a magnet. The direction of magnetic field (or the location of north and south poles) depends on the direction of current flowing through the coil. When current direction is same in both the coils then direction of magnetic field is same and they acts as if north pole of one coil is placed close to south pole of another coil. So they attract each other. When current direction is opposite in two coils then their magnetic fields are opposite and they acts as like poles of two coil are close to each other. Thus, they repel each other.