Question

Representing the stopping potential V along y-axis and $\left(1/\lambda \right)$ along x-axis for a given photocathode, the curve is a straight line, the slope of which is equal to

• A. $e/hc$
• B. $hc/e$
• C. $ec/h$
• D. $he/c$

Answer 1

The correct option is B $hc/e$

The Einstein's equation for photoelectric effect is given by , $K_{max}=h\nu -W$

or $eV=\frac{hc}{\lambda }-\frac{hc}{{\lambda }_0}$ where $\lambda =$ wavelength of absorbed photon and ${\lambda }_0=$ threshold wavelength.

So, $V=\frac{hc}{e\lambda }-\frac{hc}{e{\lambda }_0}$

Comparing this equation with general equation of straight line $y=mx+c$, we get slope, $m=hc/e$