The figure shows the variation of photocurrent $i$ with anode potential $V$ 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. Then

In a photoelectric effect experiment,light of frequency $1.5$ times the threshold frequency is made to fall on the surface of a photosensitive material. If the frequency is halved and the intensity is doubled,the number of photoelectrons emitted will be:

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

Photoelectrons from a metal do not come out with the same energy. The most appropriate explanation is:

Define threshold frequency and on which factor does threshold frequency depend?

In the photoelectric effect,the photocurrent: