A current of 4 A is flowing at 230 V in the primary coil of a transformer. If the voltage produced in the secondary coil is 2300 V and 40 % of power is lost, then the current in the secondary will be

A thin glass prism has refractive index $1.5$. The correct relation between the angle of minimum deviation $(\delta m)$ and angle of refraction $(r)$ is

In diffraction experiment from single slit, the angular width of the central maxima does NOT depend upon

To improve the resolving power of a compound microscope we should