coil of 1 turns made by a constant length current carrying wire. If number of turns makes 2 then change in magnetic field produced at its centre :-

Options

A. `200%` decreases
B. `300%` decreases
C. `300%` increases
D. `200%` increases

Answer

C

Explanation

`B_(1)=(mu_(0)I)/(2r)`
`B_(2)=(mu_(0)(2I))/(2(r//2))=4B_(1)`
`Delta B=B_(2)-B_(1)=3B_(1)`