Module Question 30 (Part C)

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Module Question 30 (Part C)

Postby lindsey_ammann_4E » Sat Oct 13, 2018 5:50 pm

Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1.
Will someone walk me through this?
30. C. What is the frequency of the incident light on the sodium metal surface?

A. 3.01 x 1014 Hz

B. 2.27 x 1038 Hz

C. 4.54 x 1058 Hz

D. 6.78 x 1014 Hz

E. None of the above

Kavya Juwadi 3C
Posts: 30
Joined: Fri Sep 28, 2018 12:25 am

Re: Module Question 30 (Part C)

Postby Kavya Juwadi 3C » Sat Oct 13, 2018 11:02 pm

From parts A and B of this problem we find out that the kinetic energy is 1.99 x 10^-19 J and the work is 2.5 x 10^-19 J. If we add the kinetic energy and work together we get the energy of the photon, which is 4.49 x 10^-19.
Energy of the photon = plank's constant x frequency
When we plug in the energy of the photon and plank's constant to the equation above, we get a frequency of 6.78 x 10^14 Hz

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