The Einstein–Planck relation for a photon states E=hf .
a. State the meaning of the term *photon*.
b. State what each of the terms in the relation mean and its unit.
c. Show that the Einstein–Planck relation can also be expressed as E=hλc .
d. Photon energies are often quoted in electronvolts, eV. Define the term *electronvolt*.
e. Calculate the energy of the following photons; give your answer in Joules and in eV.
- i A red photon of wavelength 630 nm
- ii A green photon of wavelength 532 nm
- iii A blue photon of wavelength 430 nm