Question

What is the longest wavelength of light required to remove an electron from the surface of potassium metal by the photoelectric effect if the binding energy of an electron is 1.76 ×103 kJ/mol?

Answer 1

Answer:

Wavelength, $\lambda=6.81\times 10^{-8}\ m$

Explanation:

It is given that,

The binding energy of an electron is, $E=1.76\times 10^3\ kJ/mol$

or

The binding energy of an electron is,

$E=\dfrac{1.76\times 10^3}{6.023\times 10^{23}}\times 10^3\ J$  

$E=2.92\times 10^{-18}\ J$

Let $\lambda$ is the wavelength of light required to remove an electron from the surface of potassium metal by the photoelectric effect. The energy of an electron is given by :

$E=\dfrac{hc}{\lambda}$

$\lambda=\dfrac{hc}{E}$

$\lambda=\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{2.92\times 10^{-18}}$

$\lambda=6.81\times 10^{-8}\ m$

So, the longest wavelength of light required to remove an electron from the surface of potassium metal is $6.81\times 10^{-8}\ m$. Hence, this is the required solution.