$A$ photocell is a device that:

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 $2.20\,eV$, which of these photosensitive surfaces may emit photoelectrons?

The work function of a metal is

$A$ point source causes the photoelectric effect from a small metal plate. Which of the following curves may represent the saturation photocurrent $(I)$ as a function of the distance $(r)$ between the source and the metal?

$A$ monochromatic beam of light of wavelength $400\,nm$ is incident normally upon a photosensitive surface ($25\%$ reflects and the rest is absorbed). This produces a radiation pressure of $5 \times 10^{-7}\,N/m^2$ on the surface. If $0.1\%$ of the incident photons produce photoelectrons,the corresponding saturation current will be $\dots \mu A$. (Consider the area of the photosensitive surface $= 5\,cm^2$)

Which of the following is dependent on the intensity of incident radiation in a photoelectric experiment?