## Module Question 31 and 32

Or Fisher 1I
Posts: 35
Joined: Fri Feb 02, 2018 3:00 am

### Module Question 31 and 32

Hello, I am trying to answer question 32, and I get that question 31's answer is 550.7nm, but I don't understand how to now solve 32. Could someone please help me? Thanks.
31. This and the following question relates to the same metal used in a series of photoelectric experiments.

A. If 3.607 x 10-19 J is required to remove an electron with zero kinetic energy from a metal surface, what would be the longest wavelength light that could do this?

A. 802.0 nm

B. 163.2 nm

C. 550.7 nm

D. 181.6 nm

E. None of the above

32. B. In a second experiment a shorter wavelength light source is used resulting in ejected electrons with a kinetic energy of 4.200 x 10-19 J.
What is the energy of this incident light?
What is the wavelength of this incident light?

A. 7.807 x 10-19 J, 254.4 nm

B. -5.930 x 10-20 J, 335.0 nm

C. 1.515 x 10-37 J, 131.1 nm

D. 8.588 x 10-39 J, 231.3 nm

E. None of the above

Chem_Mod
Posts: 18898
Joined: Thu Aug 04, 2011 1:53 pm
Has upvoted: 717 times

### Re: Module Question 31 and 32

Think about what's given, what's constant, and which equation to use. You know to use $E_{incidentlight} = \phi + KE_{electron}$. The same metal is used, so work function is constant. You know work function because it is the amount of energy required to remove an electron from metal plate at zero kinetic energy. You know the kinetic energy of emitted electron. Find the missing variable.