Threshold frequency for a metal is $10^{15} \ Hz$. Light of $\lambda = 4000 \ \mathring{A}$ falls on its surface. Which of the following statements is correct?

The curve between the work function of a metal $(\phi_o)$ and its temperature $(T)$ will be:

$A$ 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:

The threshold wavelength for the emission of photoelectrons from a material is $5200\, \text{\AA}$. Which of the following monochromatic light sources will cause the emission of photoelectrons from this surface?

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

Photoelectric effect occurs when ultraviolet rays are incident on a metal plate. It does not occur when which of the following are incident?