The magnets of two suspended coil galvanometer are of the same strength so that they produce identical uniform magnetic fields in the region of the coils. The coil of the first one is in the shape of a square of side a and that of the second one is circular of radius `(a)/(sqrtpi)`. When the same current is passed throught the coils, the ratio of the torque experienced by the first coil to that rxperienced by the second one is

Options

A. `1:(1)/(sqrtpi)`
B. `1:1`
C. `pi:1`
D. `1:pi`

Explanation

In this case applied torque `(tau)` does not depend on the shape of the coil but the area of cross-section (A) of the coil.
`:.(tau_(1))/(tau_(2))=(A_(1))/(A_(2))=(a^(2))/(pi((a)/(sqrtpi))^(2))=1`
or, `tau_(1):tau_(2)=1:1`