Question

At a point P on the axis of a current carrying circular coil of radius R, the magnetic field is B. If the distance of point P from the centre of the coil is $R\sqrt{15}$, then the magnetic field at a point Q on the axis of the coil which is at a distance of $R\sqrt{3}$ from the centre of the coil is}

• A. $B\sqrt{5}$
• B. $5B$
• C. $B\sqrt{8}$
• D. $8B$

Hint:

For axial magnetic field problems, first write \[ B=\frac{\mu_0IR^2}{2(R^2+x^2)^{3/2}} \] and then use ratios. Most calculations become very simple.

Answer 1

The Correct Option is B