The work functions of Caesium $(Cs)$, Potassium $(K)$, and Sodium $(Na)$ are $2.14 \ eV$, $2.30 \ eV$, and $2.75 \ eV$ respectively. If incident electromagnetic radiation has an incident energy of $2.41 \ eV$, which of these photosensitive surfaces may emit photoelectrons?

Light of intensity $10^{-5} \; W m^{-2}$ falls on a sodium photo-cell of surface area $2 \; cm^2$. Assuming that the top $5$ layers of sodium absorb the incident energy,estimate the time required for photoelectric emission in the wave-picture of radiation. The work function for the metal is given to be about $2 \; eV$. What is the implication of your answer?

Explain the effect of the frequency of incident radiation in the experiment of the photoelectric effect.

Threshold frequency for a metal is $10^{15} \ Hz$. Light of $\lambda = 4000 \ \mathring{A}$ falls on its surface. Which of the following statements is correct?

For photoelectric emission, tungsten requires light of $2300 \mathring{A}$. If light of $1800 \mathring{A}$ wavelength is incident, then emission:

When the intensity of incident light increases: