Question

Graph between kinetic energy of photoelectron $K{E}_{(}max)$ Vs frequency(v) of an incident photon is given when light is incident on a metal plate during photoelectric experiment : Wavelength of light corresponding to frequency $v_1$ is 200 nm. If mmonochromatic light of wavelength 100nm is incident on metal plate then $K.E{.}_{(}max)$ of ejected photoelectric is:

• A. $1\times {10}^{-27}J$
• B. $9.9\times {10}^{-17}J$
• C. $9.9\times {10}^{-19}J$
• D. $1\times {10}^{-22}J$

Answer 1

The correct option is C $9.9\times {10}^{-19}J$

$K_{max}=hc(\frac{1}{\lambda }-\frac{1}{{\lambda }_0})$

$=6.6\times {10}^{-34}\times 3\times {10}^8(\frac{1}{100}-\frac{1}{200})\times {10}^{-9}$

$=19.8\times {10}^{-26}\left(\frac{2-1}{200}\right)\times {10}^{-9}$

$=19.8\times {10}^{-26}\frac{1}{2}\times {10}^{-7}$

$=9.9\times {10}^{-26}\times {10}^7$

$=9.9\times {10}^{-19}$ Joule