As the intensity of incident light increases,

$A$ photosensitive material is at $9\,m$ to the left of the origin and the source of light is at $7\,m$ to the right of the origin along the $x$-axis. The photosensitive material and the source of light start from rest and move,respectively,with $8\widehat{i}\,m/s$ and $4\widehat{i}\,m/s$. The ratio of intensities at $t = 0$ to $t = 3\,s$ as received by the photosensitive material is:

When yellow light is incident on a surface,no electrons are emitted,while green light can emit them. If red light is incident on the surface,then:

What is a photoelectron?

Assertion : The photoelectrons produced by a monochromatic light beam incident on a metal surface have a spread in their kinetic energies.
Reason : The work function of the metal varies as a function of depth from the surface.

Threshold frequency for a metal is $15 \times 10^{14} \, Hz$. The light of wavelength $6000 \, \text{Å}$ falls on the metal surface. Then photoelectrons [velocity of light in air, $c = 3 \times 10^8 \, m/s$]: