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  • A photon with a wavelength of 400 nm strikes a metal surface, producing an electron with a kinetic energy of 2.5 eV. What is the work function of the metal surface?<stro

A photon with a wavelength of 400 nm strikes a metal surface, producing an electron with a kinetic energy of 2.5 eV. What is the work function of the metal surface?

Option: 1

0.5 eV


Option: 2

2.5 eV


Option: 3

3.3 eV


Option: 4

4.1 eV


Answers (1)

best_answer

The energy of a photon is given by

E= hc/\lambda.

Therefore, the energy of a photon with a wavelength of 400 nm is given by
\\ E= \left ( 6.626\times 10^{-34}Js \right )\left ( 3.00\times 10^{8}m/s \right )/\left ( 400\times 10^{-9}m \right )= 4.97 \times 10^{-19}J \\ E=3 eV.

The kinetic energy of the emitted electron is given by

 K E=h f-W

where W is the work function of the metal surface.

Solving for W, we get
W=h f-K E=(3-2.5) \mathrm{eV}= 0.5 \mathrm{eV}
 

Posted by

Suraj Bhandari

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