Question:
An electron initially at rest is accelerated through a potential difference. It is then brought to rest in a collision, and all of its kinetic energy is converted into a single photon of electromagnetic radiation. Which one of the following quantities is not required to find a value for the wavelength of the photon?
A The mass of the electron
B The charge on the electron
C The velocity of electromagnetic waves
D The value of the potential difference
Why is the answer A?