Question

The maximum kinetic energy of the emitted frequency v of incident radiation is plotted as shown in fig. This graph help us in determining the following physical quantities

• A. Work function of the cathode-metal
• B. Threshold frequency
• C. Planck's constant
• D. Charge on an electron

Answer 1

Answer: (A), (B), (C)

The correct options are
A Work function of the cathode-metal
B Threshold frequency
C Planck's constant

The Einstein's equation for photoelectric effect is given by, $E_{k}max=h\nu -W$ where $E_{k}max=$ maximum kinetic energy of photoelectron , $h=$ Planck's constant, $\nu =$ frequency of the incident light and $W=$ work function of metal.

Comparing the general equation of straight line $y=mx+c$ , we get

slope $m=h$ and intercept $c=-W$

Thus we can calculate Planck's constant h from the slope of the line and work function from the intercept.

Since $W=h{\nu }_0$ so we can calculate threshold frequency $\left({\nu }_0\right)$ from work function.