(a)(i) Explain the terms: photoelectric emission and threshold frequency; (ii) Einstein's photoelectric equation can be written as \(E = hf - hf_{o}\) What does each of the symbols used in the equation above represent?

(b) Calculate the frequency of the proton whose energy is required to eject a surface electron with a kinetic energy of \(1.97 \times 10^{-16} eV\) if the work function of the metal is \(1.33 \times 10^{-16}eV\). \((1 eV = 1.6 \times 10^{-18}J; h = 6.60 \times 10^{-34}JS)\).

(c) In a photoelectric cell, no electrons are emitted until the threshold frequency of light is reached. Explain what happens to the energy of the light before emission of electrons begins. State one factor that may affect the numbers of emitted electrons.

(d) Explain what is meant by the duality of matter, illustrating your answer with observation phenomena.