Explain what is meant by a photon.
An X-ray photon of energy 
is incident on an isolated stationary electron, as illustrated in the figure below.
The photon is deflected elastically by the electron through angle 
. The deflected photon has a wavelength of 
.
On the figure above, draw an arrow to indicate a possible initial direction of motion of the electron after the photon has been deflected.
Calculate
the energy of the deflected photon,
the speed of the electron after the photon has been deflected.
Explain why the magnitude of the final momentum of the electron is not equal to the change in magnitude of the momentum of the photon.
that is directly proportional to its frequency 
, the energy is given by the equation:
is Planck’s constant.
.
.
