In a photo cell,the photo-electrons emission takes place

What is the phenomenon of the photoelectric effect?

$A$ 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 $= 5\,cm^2$)

The figure represents the graph of photoelectric current $I$ versus applied voltage $(V)$. The maximum kinetic energy of the emitted photoelectrons is

Photoelectric effect is produced by a point source on a small metal plate. Which of the following curves represents the saturation photoelectric current as a function of the distance between the source and the metal?

When monochromatic radiation of intensity $I$ falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are $N$ and $K$ respectively. If the intensity of radiation is $2I$, the number of emitted electrons and their maximum kinetic energy are respectively