An atom can become excited by the absorption of photons. Explain why only photons of certain frequencies cause excitation in a particular atom.
Electrons in an atom occupy discrete energy levels. An electron can only be excited to another level if it absorbs the exact amount of energy as the difference between the two levels. Therefore the energy of the photon it absorbs needs to be of a specific energy to excite it and, as E = hf, its energy needs to be a specific frequency.
AJ
Related Physics A Level answers
All answers ▸Determine a vector expression for the position of a particle whose velocity is (3t^2 - 8)i + 5j m/s.
A box is pulled with a rope at 26° to the horizontal and a tension of 120N. What is the work done in pulling it 5 metres?
How does conservation of momentum work when at least one of the bodies in the problem changes mass?
Why is a pendulum with a bob of the same size but larger mass than another bob damped more lightly?