Question

What is the maximum kinetic energy of ejected electrons when photons of wavelength 300 nm hit a metal that has a work function of 1.13 ev? A. 0.50 ev B. 1.0 ev C. 2.0 ev D. 3.0 eV E. 4.0 ev

Answer 1

Explanation:

Given that,

Wavelength of the photon, $\lambda=300\ nm=3\times 10^{-7}\ m$

Work function of the metal, $\phi=1.13\ eV=1.81\times 10^{-19}\ J$

We need to find the maximum kinetic energy of the ejected electrons. It can be calculated using Einstein's photoelectric equation as :

$hf=E_k+\phi$

$E_k=hf-\phi$

$E_k=h\dfrac{c}{\lambda}-\phi$

$E_k=6.63\times 10^{-34}\times \dfrac{3\times 10^8}{3\times 10^{-7}}-1.81\times 10^{-19}$

$E_k=4.82\times 10^{-19}\ J$

$E_k=3.01\ eV$

or

$E_k=3\ eV$

So, the maximum kinetic energy of the ejected electrons is 3 ev. Hence, this is the required solution.