Energy:
$E=h\nu =\frac{hc}{\lambda }$
Momentum:
$p=\frac{h}{\lambda }=\frac{E}{c}$

Einstein's photoelectric equation :
$K_{max}=\frac{hc}{\lambda }-\phi =h\nu -\phi$
The kinetic energy of the photoelectron coming out may be anything between zero and $(E-\phi )$ where $E=\frac{hc}{\lambda }$ is the energy supplied to the individual electrons.
$K_{max}=E-\phi$

The smallest magnitude of the anode potential which just stops the photocurrent is called the stopping potential.
This potential should stop even the ost energitic photoelectron. Hence 
Tha value of maximum kinetic energy should be equal to $e{V}_0$
We know $K_{m}ax=h\nu -\varphi =\frac{hc}{\lambda }-\varphi$
$V_0=\frac{hc}{\lambda e}-\frac{\varphi }{e}$

Example: An electron of charge e and mass m is accelerated from rest by a potential difference V. Find the de-Broglie wavelength.

Solution:
$\frac{1}{2}m{v}^2=eV$
$mv=\sqrt{2eVm}$
So de-broglie wavelength
$\lambda =\frac{h}{mv}$
$=\frac{h}{\sqrt{2meV}}$

The maximum kinetic energy of the photoelectrons varies linearly with the frequency of incident radiation, but is independent of its intensity.
For a frequency of $\nu$ of incident radiation, lower than the threshold frequency ${\nu }_0$ no photoelectric emission is possible even if the intensity is large.

$K_{max}=\frac{hc}{\lambda }-\phi =\frac{1}{2}m{v}_{max}^2$
then $v_{max}=\sqrt{\frac{2(\frac{hc}{\lambda }-\phi )}{m}}$
The work function of a metal surface is 1 eV. A light of wavelength 3000$A^0$ is incident on it. The maximum velocity of the photoelectrons is found as:

The maximum K.E with which electrons comes out,

$\frac{hc}{\lambda }-1eV=\frac{1}{2}m{v}^2$

$\Rightarrow \frac{2\times 3.14\times 1.6\times 10^{-19}\times 10^{31}}{9.1}=v^2$

$v^2=1.10461\times 10^{12}$

$\Rightarrow v=1.05\times 10^6$

$\Rightarrow v=10^6$

De Broglie's wavelength is the wavelength associated with a massive particle,hypothesized by De Broglie that explains Bohr's quantised orbits by bringing in the wave-particle duality.  It is written as
$\lambda =\frac{h}{mv}$ (de broglie wavelength)