The telescopes, for a given wavelength, the objectives with large aperture are used for

A circuit having a self inductance of 1 henry carries a current of 1 A . To prevent the sparking when the circuit is broken, a capacitor which can withstand 500 V is connected across the switch. What is the minimum value of the capacitance of the capacitor?

An air column in a closed organ pipe vibrating in unison with a fork, produces second overtone. The vibrating air column has

At certain place a magnet makes 30 oscillations per minute. At another place if the magnetic induction is increased by two times the magnetic induction at first place, then the time period of same magnet will be