In an isobaric process of an ideal gas, the ratio of work done by the system (W) during the expansion and the heat exchanged $(\mathrm{Q})$ is $\left(\gamma=\frac{\mathrm{C}_{\mathrm{p}}}{\mathrm{C}_{\mathrm{v}}}\right)$

A long solenoid carrying a current produces magnetic field B along its axis. If the number of turns per cm are tripled and the current is made $\left(\frac{1}{4}\right)^{\text {th }}$ then the new value of magnetic field will be

An astronomical telescope has a large aperture to

A sonometer wire is in unison with a tuning fork of frequency ' $n$ ' when it is stretched by a weight of specific gravity ' $d$ '. When the weight is completely immersed in water, ' $x$ ' beats are produced per second, then