Question

Light with a wavelength of 5.0 · 10-7 m strikes a surface that requires 2.0 EV to eject an electron. Calculate the energy, in electron volts, of one incident photon._____ eV6.9 x 10 -302.52.5 x 10 -306.2 x 10 -13

Answer 1

Given data:

* The wavelength of the incident light is,

`\lambda=5*10^(-7)\text{ m}`

Solution:

The energy of the incident photon is,

`E=(hc)/(\lambda)`

where h is a planck's constant, and c is the speed of light,

Substituting the known values.

`E=(6.626*10^(-34)*3*10^8)/(5*10^(-7))`

By calculations,

`\begin{gathered} E=4*10^(-19)\text{ J} \\ E=(4*10^(-19))/(1.6*10^(-19)) \\ E=2.5\text{ eV} \end{gathered}`

Thus, the energy of an incident photon is 2.5 eV.

Hence, second option is the correct answer.