Simple microscope is used to see the object first in blue light and then a red light. Due to the change from blue to red light, its magnifying power

The inductive reactance of a coil is ' $R$ ' $\Omega$. If inductance of a coil is tripled and frequency of a.c supply is also tripled, then new inductive reactance will be

A musical instrument X produces sound waves of frequency n and amplitude A. Another musical instrument $Y$ produces sound waves of frequency $\frac{n}{3}$. The waves produced by $x$ and $y$ have equal energies. The amplitude of waves produced by Y will be

In the block diagram of simple rectifier circuit, from a variable a.c. voltage, constant d.c. voltage is obtained. The correct order of operation is