How will the magnetic field intensity, at the centre of a circular coil carrying currents, change if the current through the coil is doubled and radius of the coil is halved ?

Explanation

We know, `B=(mu_(0)NI)/(2r)`
` :. (B_(1))/(B_(2))=(I_(1))/(I_(2))*(r_(2))/(r_(1))=(1)/(2)xx(1)/(2)=(1)/(4) or, B_(2)=4B_(1)`