In a photoemissive cell with executing wavelength $\lambda $, the fastest electron has speed $v.$ If the exciting wavelength is changed to $\frac{{3\lambda }}{4}$, the speed of the fastest emitted electron will be
$v\;{(3/4)^{1/2}}$
$v\;{(4/3)^{1/2}}$
$ < v\;{(4/3)^{1/2}}$
$ > v\;{(4/3)^{1/2}}$
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 :
What is velocity of photon ?
In a dark room of photography, generally red light is used. The reason is
The momentum of the photon of wavelength $5000\,\mathring A$ will be
Do all the electrons that absorb a photon come out as photoelectrons ?