State what the photoelectric effect means.
The photoelectric effect is studied with two clean metal plates. One plate is made of metal X and the other is made of metal Y. Metal X has work function energy $\Phi$. Metal Y has work function energy $2\Phi$. Metal X has threshold frequency $F$. State an expression, in terms of either or both of $\Phi$ and $F$, for the threshold frequency of metal Y.
State an expression, in terms of either or both of $\Phi$ and $F$, for the Planck constant.
The maximum kinetic energy $E_K$ of photoelectrons is found for each plate in (b) at different frequencies $f$ of the incident radiation. On Fig. 9.1, sketch how $E_K$ varies with $f$ for each plate. Label your lines X and Y to show which line represents which plate.