Question

The stopping potential for photoelectric emission from a metal surface is plotted along Y-axis and frequency $\nu$ of incident light along X-axis. A straight line is obtained as shown. Planck's constant is given by

• A. slope of the line
• B. product of slope of the line and charge on the electron
• C. intercept along Y-axis divided by charge on the electron
• D. product of intercept along X-axis and mass of the electron

Answer 1

Answer: (B)

Einstein's photoelectric equation is
$V=\frac{h\nu }{e}-\frac{h{\nu }_0}{e}$
Here, the slope of the line $=\frac{h}{e}$
$\Rightarrow h=$ Planck's constant = slope $\times e$
Hence, Planck's constant is product of slope of the line and charge on the electron.