A $160 \,W$ light source is radiating light of wavelength $6200 \,\mathring A$ uniformly in all directions. The photon flux at a distance of $1.8 \,m$ is of the order of .......... $m ^{-2} s ^{-1}$ (Planck's constant $\left.=6.63 \times 10^{-34} \,J - s \right)$
$10^2$
$10^{12}$
$10^{19}$
$10^{25}$
Dual nature of radiation is shown by
The momentum of a photon with energy $20\, eV$ is
A $200\, W$ sodium street lamp emits yellow light of wavelength $0.6\, \mu \,m$. Assuming it to be $50\%$ efficient in converting electrical energy to light, the number of photon of yellow light it emits per second is
Photo-electric effect can be explained by
When light falls on a metal surface, the maximum kinetic energy of the emitted photo-electrons depends upon