A $5$ watt source emits monochromatic light of wavelength $5000\; \mathring A$. When placed $0.5\; m$ away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of $1.0\;m$, the number of photo electrons liberated will
be reduced by a factor of $4$
be reduced by a factor of $2$
be reduced by a factor of $8$
be reduced by a factor of $16$
The number of photons per second on an average emitted by the source of monochromatic light of wavelength $600\, \mathrm{~nm}$, when it delivers the power of $3.3 \times 10^{-3}$ $watt$ will be : $\left(\mathrm{h}=6.6 \times 10^{-34}\, \mathrm{Js}\right)$
A pulse of light of duration $100 \ ns$ is absorbed completely by a small object initially at rest. Power of the pulse is $30 \ mV$ and the speed of light is $3 \times 10 ^8\ ms ^{-1}$. The final momentum of the object is :
When monochromatic radiation of intensity $I$ falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are $N$ and $K$ respectively. If the intensity of radiation is $2I$, the number of emitted electrons and their maximum kinetic energy are respectively
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
According to photon theory of light which of the following physical quantities associated with a photon do not/does not change as it collides with an electron in vacuum