Question

In a photoelectric experiment, the kinetic energy of photoelectrons was plotted against the frequency of the incident radiation $\left(\nu \right)$, as shown in the figure. Which of the following statements is correct?

• A. The threshold frequency is ${\nu }_1$
• B. The slope of the line is equal to the Planck's constant.
• C. As the frequency of the incident wavelength increases beyond the threshold frequency, the kinetic energy of the photoelectrons decreases.
• D. It is impossible to obtain such a graph.

Answer 1

The correct option is B The slope of the line is equal to the Planck's constant.

We know that, $h\nu =h{\nu }_o+KE$
$KE=h\nu -h{\nu }_o$
$\text{On comparing the above equation with}\text{the equation of a straight line}(y=mx+c),$
$\text{the slope of the graph between KE}\text{and}\nu \text{is Planck’s Constant.}$