Dual Nature Of Radiation And Matter - Modern Physics - Physics Previous Year Questions

A ray of light with wavelength $\lambda$ is incident on three different photoelectric cells namely 1,2 and 3 . The threshold wavelength of these photoelectric cells are $\lambda_1, \lambda_2$, and $\lambda_3$, respectively and the magnitude of stopping potentials of these cells are $V_1, V_2$ and $V_3$, respectively. The relation between $\lambda$ and threshold wavelengths are $\lambda_1<\lambda, \lambda_2>\lambda$ and $\lambda_3 \gg \lambda$. The correct option is:

A beam of light falls on a metal surface such that photo-electrons are generated. If power of the light source starts to decrease linearly with time $t$, then variation of the photocurrent $I$ and magnitude of the stopping potential $|V|$ with time is best represented by:

A photon and an electron, each of 20 eV energy, move in free space. The ratio of linear momentum of electron $\mathrm{p}_{\mathrm{e}}$ to that of photon $\mathrm{p}_{\mathrm{Ph}}, \frac{\mathrm{p}_{\mathrm{e}}}{\mathrm{p}_{\mathrm{Ph}}}$ is:

[Take speed of light $=3 \times 10^8 \mathrm{~ms}^{-1}$, charge of electron $=-1.6 \times 10^{-19} \mathrm{C}$ and mass of electron $=9 \times 10^{-31} \mathrm{~kg}$ ]