A photo sensitive material is at $9\,m$ to the left of the origin and the source of light is at $7\,m $ to the right of the origin along $x$ -axis. The photosensitive material and the source of light start from rest and move, respectively, with $8 \widehat i \, m / s$ and $4 \widehat i \, m / s$ . The ratio of intensities at $t = 0$ to $t = 3\,s$ as received by the photosensitive material is :-
$16 : 1$
$1 : 16$
$2 : 7$
$7 : 2$
The work function of aluminium is $4.2eV.$ If two photons, each of energy $3.5 eV$strike an electron of aluminium, then emission of electrons will be
If $c$ is the velocity of light in free space, the correct statements about photon among the following are:
$A$. The energy of a photon is $E=h v$.
$B$. The velocity of a photon is $c$.
$C$. The momentum of a photon, $p=\frac{h v}{c}$.
$D$. In a photon-electron collision, both total energy and total momentum are conserved.
$E$. Photon possesses positive charge.
Choose the correct answer from the options given below:
An electron and a photon each have a wavelength of $1.00\; nm$. Find
$(a)$ their momenta,
$(b)$ the energy of the photon, and
$(c)$ the kinetic energy of electron.
The energy of a photon of wavelength $\lambda $ is given by