$10^{20}$ photons of wavelength 660 nm are emitted per second from a lamp. The wattage of the lamp is (Planck's constant $=6.6 \times 10^{-34} \mathrm{Js}$ )
The apparent coefficient of expansion of a liquid, when heated in a copper vessel is $C$ and when heated in silver vessel is $S$. If $A$ is linear coefficient of expansion of copper, then linear coefficient of expansion of silver is
The equation of a stationary wave along a stretched string is given by $y=5 \sin \frac{\pi x}{3} \cos 40 \pi t$. Here $x$ and $y$ are in cm and $t$ in second. The separation between two adjacent nodes is
Temperature of a body $\theta$ is slightly more than the temperature of the surrounding $\theta_0$. Its rate of cooling $(R)$ versus temperature of the body $(\theta)$ is plotted. Its shape would be



