Video Module Assessment

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Naomi 3G
Posts: 9
Joined: Wed Sep 18, 2019 12:20 am

Video Module Assessment

Postby Naomi 3G » Sun Oct 20, 2019 9:51 pm

Can someone explain this question in the video model assessment.
Molybdenum metal must absorb radiation with a minimum frequency of 1.09*10^15s^-1 before is can emit an electron from its surface.
The minimum energy needed to produce this effect id 7.22*10^-19J
If molybdenum is irradiated with 194 nm light, what is the maximum possible kinetic energy of the emitted electrons?
I got 6.41 J, but that seems to be the wrong answer.
Maybe I confuse the meaning of irradiated.

Jade Hinds 2B
Posts: 75
Joined: Tue Sep 10, 2019 12:16 am

Re: Video Module Assessment

Postby Jade Hinds 2B » Sun Oct 20, 2019 10:00 pm

step 1= convert nm to m
1nm= 10^9m
so... 194nm = 1.94 x 10^-7m

step 2= use speed of light formula: c=(wavelength)(frequency)
3.10 x 10^8= (1.94 x 10^-7m)(frequency)
frequency= 1.546 x 10^15

Now you can plug the frequency into the formula for kinetic energy: E=hv
E= (6.626 x 10^-34)(1.546 x 10^15)= 1.025 x 10^-18 J

Thats what I got! Hope my steps help you get the right answer.

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