In a photoelectric effect experiment,three different metal plates $p, q,$ and $r$ have work functions $\phi_p = 2.0 \ eV, \phi_q = 2.5 \ eV,$ and $\phi_r = 3.0 \ eV$. The incident light beams have wavelengths $\lambda_p = 550 \ nm, \lambda_q = 450 \ nm,$ and $\lambda_r = 350 \ nm$. The intensity of light is the same for each plate. The correct $I-V$ graph for the experiment is: $[hc = 1240 \ eV \ nm]$

Two parallel discs are connected by a rigid rod of length $L=0.5 \,m$ centrally. Each disc has a slit oppositely placed as shown in the figure. $A$ beam of neutral atoms is incident on one of the discs axially at different velocities $v$,while the system is rotated at an angular speed of $600 \,rev/s$,so that atoms only with a specific velocity emerge at the other end. Calculate the two largest speeds (in $m/s$) of the atoms that will emerge at the other end.

Photoelectric effect experiments are performed using three different metal plates $p, q$ and $r$ having work functions $\phi_p=2.0 \ eV, \phi_q=2.5 \ eV$ and $\phi_r=3.0 \ eV$,respectively. $A$ light beam containing wavelengths of $550 \ nm, 450 \ nm$ and $350 \ nm$ with equal intensities illuminates each of the plates. The correct $I-V$ graph for the experiment is:

The dual nature of light is exhibited by

Find the number of photons emitted per second from a source of light which results in a photocurrent with drift velocity of $1.5 \ m/s$ in a conductor with cross-section area $0.25 \ m^2$ and volume density of electrons $10^{20} \ m^{-3}$. (Assume that $60\%$ of photons emitted result in electron emission).

The radiation corresponding to the $3 \rightarrow 2$ transition of a hydrogen atom falls on a gold surface to generate photoelectrons. These electrons are passed through a magnetic field of $5 \times 10^{-4} \, T$. Assume that the radius of the largest circular path followed by these electrons is $7 \, mm$. The work function of the metal is $..... \, eV$. (Mass of electron $= 9.1 \times 10^{-31} \, kg$)