Photon Physics Example

What is a photon?

A photon is a wave packet of energy such as in electromagnet radiation.

Below is an illustration of the relationship between E, the energy of a photon and its wavelength which is:

where E is measured in J and the wavelength is measured in nm.

If two metal electrodes A and B are sealed into an evacuated glass envelope and a potential difference V, measured using the voltmeter, is applied between them as shown below.

B is then illuminated with monochromatic light of wavelength 365 nm and I, the current in the circuit, is measured for various values of V. The results are shown below.

From this graph, deduce the p.d. required to stop photoelectric emission from B.

Calculate the maximum kinetic energy of the photoelectrons.