Two sources of light emit with a power of $200 \mathrm{~W}$. The ratio of number of photons of visible light emitted by each source having wavelengths $300\  \mathrm{nm}$ and $500 \mathrm{~nm}$ respectively, will be :

The eye can detect  $5 ×10^4$ photons per square metre per sec of green light ($\lambda$ $= 5000\ \mathop A\limits^o $) while the ear can detect ${10^{ - 13}}\,(W/{m^2})$. The factor by which the eye is more sensitive as a power detector than the ear is close to

Both the nucleus and the atom of some element are in their respective first excited states. They get de-excited by emitting photons of wavelengths $\lambda _N,\,\lambda _A$  respectively. The ratio $\frac{{{\lambda _N}}}{{{\lambda _A}}}$  is closest to

When light falls on a metal surface, the maximum kinetic energy of the emitted photo-electrons depends upon

The number of photons emitted by a $10\,watt$ bulb in $10\,second,$ if wavelength of light is $1000\,\,\mathop A\limits^o ,$ is

A photon, an electron and a uranium nucleus all have the same wavelength. The one with the most energy