(a)[2]
State the meaning of the photoelectric effect.
(b)
The photoelectric effect is studied in two stages with the circuit shown in Fig. 9.1.
(b(i))[3]
Explain, with reference to photons, why $V_s$ varies with the frequency of the incident electromagnetic radiation.
(b(ii))[3]
State three quantitative conclusions that can be obtained from the data in Fig. 9.2 and Fig. 9.3. Use the space for any working.