Light with a frequency of $1.5$ times the threshold frequency is incident on a photosensitive material. If the frequency is halved and the intensity is doubled,what will be the photoelectric current?

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?

Assertion : Kinetic energy of photoelectrons emitted by a photosensitive surface depends upon the intensity of incident photon.
Reason : The ejection of electrons from a metallic surface is possible with a frequency of incident photon below the threshold frequency.

Which one of the following is true in photoelectric emission?

The figure shows the variation of photocurrent with anode potential for a photo-sensitive surface for three different radiations. Let ${I_a}, {I_b}$ and ${I_c}$ be the intensities and ${f_a}, {f_b}$ and ${f_c}$ be the frequencies for the curves $a, b$ and $c$ respectively.

Which of the following phenomena exhibits the particle nature of light?