Question

Answer the attachment........​

Answer 1

Option a and c are right.

From photo electric effect, $\large\rm { eV = \frac {hc}{ \lambda} - \phi }$

where V is stopping potential and ϕ= work function.

slope, $\large\rm { m = \tan \theta = hc/e}$ (compare above equation with y=mx−c)

$\large\rm { if \ V = 0 \implies \frac { \phi}{hc} = \frac {1}{\lambda}}$

Now , the given values in graph.... (values of $\large\rm { \frac {\phi}{hc}})$

$\large\rm { \frac { \phi_{1}}{hc} = 0.001}$

$\large\rm { \frac { \phi_{2}}{hc} = 0.002}$

$\large\rm { \frac { \phi_{3}}{hc} = 0.004}$

Thus, $\large\rm { \phi_{1} : \phi_{2} : \phi_{3} = 1:2:4}$

also, $\large\rm { \phi = \frac {hc}{ \lambda_{0}}}$ where $\large\rm { \lambda_{0}}$ be the threshold wavelength.

As the wavelength of violet colour is around 400 nm so only metal 2 can eject violet colour light but not metal 3.

Thus, options A and C is right.