Two concentric coils carry the same current in opposite directions. The diameter of the inner coil is equal currents. The outer coil. If the magnetic field produced by the outer coil at the common centre are `1 T`, the net field at the centre is

Options

A. `1T`
B. `2T`
C. `3T`
D. `4T`

Answer

A

Explanation

`B_(1)=(mu_(0)i)/(2r), ox`
`B_(2)=(mu_(0)i)/(2.2r)=(mu_(0)i)/(4r), o.`
`(mu_(0)i)/(4r)=1T`
`B_(0)=B_(1)-B_(2)=(mu_(0)i)/(4r)=1T`