Light from a source travels out with a velocity $c$. If the source moves away from the observer with a velocity $v$,then the relative velocity of light with respect to the observer is

Which of the following has a mass closest in value to that of the positron? $(1\;a.m.u = 931\;MeV)$

Which of the following phenomena cannot be explained by the wave theory of light?

The frequency of a photon having energy $66 \ eV$ is:

$A$ radio station broadcasts at a wavelength of $300 \ m$. If the radiating power of the transmitter is $10 \ kW$,then the number of photons emitted per second is:

Calculate the number of photons entering the eye of a duck per second,corresponding to the minimum intensity of white light $(\sim 10^{-10} \ W/m^2)$. Take the area of the duck's eye as $0.4 \ cm^2$ and the average frequency of white light as $6 \times 10^{14} \ Hz$.