State what is meant by a photon.
Describe the appearance of a visible line emission spectrum, as seen using a diffraction grating.
The lowest electron energy levels in an isolated hydrogen atom are shown in the figure below.
(not to scale)
An electron is initially at the energy level 
. State the total number of different wavelengths that may be emitted as the electron de-excites (loses energy).
Photons resulting from electron de-excitation from the energy level are incident on the surface of a sample of platinum. Platinum has a work function energy of 
. Determine
the maximum kinetic energy, in 
, of a photoelectron emitted from the surface of the platinum,
the wavelength of the photon producing the photoelectron in (ii) part 1.
that is directly proportional to its frequency 
, the energy is given by the equation:
is Planck’s constant.
.
.
