Question

A horizontal overhead power lines carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current `1*5m` below the line?
A. `1.2 xx10^(-5)`T perpendicularly outward to the plane of paper
B. `1.9 xx10^(-5)T` perpendicularly outward to the plne of paper
C. `2.6xx10^(-5)T` perpendicularly inward to the plane of paper
D. `2.6 xx10^(-5)T` perpendicularly inward to the plane of paper

Answer 1

Correct Answer - A
Given I=90 A and r=1.5 m here point P is below the power line however we have to find the magnetic field and its direction
The magnitude of magnetic field
`B=(mu_(0))/(4pi),(2I)/(r )`
`=(10^(-7)xx2xx90)/(1.5)=1.2 xx10^(-5)T`
The direction of magnetic field is given by maxwell s right hand rule so the direction of magnetic field at poitn p due to the flowing current is perpendicularly outward to the plane of paper