Sapling #4

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StephanieGrigorian2J
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Joined: Wed Sep 30, 2020 10:01 pm

Sapling #4

Postby StephanieGrigorian2J » Sun Nov 01, 2020 8:29 pm

HI! I was able to do the first part of this question by finding the work function but I can't seem to figure out the second question:
"A metal was exposed to photons at a frequency of 1.11x10^-15 s^-1, electrons were emitted with a maximum kinetic energy of 3.60x10^-19 J. Calculate the work function. What is the maximum number of electrons that could be ejected from this metal by a burst of photons (at some other frequency) with a total energy of 2.63x10^-7 J?"

Cooper Kinne 2E
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Joined: Wed Sep 30, 2020 9:59 pm

Re: Sapling #4

Postby Cooper Kinne 2E » Sun Nov 01, 2020 8:42 pm

Hey! I believe you just need to divide the total energy by the work function you got in the previous step (energy/energy needed per electron removed= max amount of electrons that could be removed)

Lilly Catarozoli 1B
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Re: Sapling #4

Postby Lilly Catarozoli 1B » Sun Nov 01, 2020 8:43 pm

You just need to divide the total energy by the work function from the step yu did before and then you should get the answer!

Sarah Huang 3A
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Re: Sapling #4

Postby Sarah Huang 3A » Sun Nov 01, 2020 8:44 pm

Stephanie Grigorian 2C wrote:HI! I was able to do the first part of this question by finding the work function but I can't seem to figure out the second question:
"A metal was exposed to photons at a frequency of 1.11x10^-15 s^-1, electrons were emitted with a maximum kinetic energy of 3.60x10^-19 J. Calculate the work function. What is the maximum number of electrons that could be ejected from this metal by a burst of photons (at some other frequency) with a total energy of 2.63x10^-7 J?"


Hi Stephanie!

With the answer you got for the previous part, you use it to divide the total energy they gave you since you know the work function to remove an electron. By dividing the total energy by the work function you found, you'll get the total amount of electrons that will be ejected.

And for clarification, the total energy is the total amount of energy that the burst of photons give altogether, so you don't need to worry about the energy of each photon from that singular burst.

I hope that helps!

StephanieGrigorian2J
Posts: 93
Joined: Wed Sep 30, 2020 10:01 pm

Re: Sapling #4

Postby StephanieGrigorian2J » Sun Nov 01, 2020 8:45 pm

Thank you so much for the help guys! :)

rhettfarmer-3H
Posts: 101
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Re: Sapling #4

Postby rhettfarmer-3H » Sun Nov 01, 2020 11:30 pm

So the work function is found using the basic equation Ek=ep-work function. So to E of the photon convert the frequency to energy as we have been doing with the e=hv. Then basic math. As we arrange the value to the correct spot. Then to get the photons remember E of the photon is J/Photon so when you divide it by Joules it turns out to be just photons.

IreneSeo3F
Posts: 87
Joined: Wed Sep 30, 2020 9:31 pm

Re: Sapling #4

Postby IreneSeo3F » Sun Nov 01, 2020 11:42 pm

For the second part of the question, you would divide the total energy by the value you got for the work function. Total Energy (J) / Work Function (J/photon) = Number of electrons (photons)

Juliana Rosales 1H
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Re: Sapling #4

Postby Juliana Rosales 1H » Sun Nov 08, 2020 10:46 pm

I had the same trouble with this problem but when i tried to use the equation I still couldn't get the right answer. I was confused about the second part too because I didn't know what to do lol.

Diana Aguilar 3H
Posts: 90
Joined: Wed Sep 30, 2020 9:50 pm

Re: Sapling #4

Postby Diana Aguilar 3H » Sun Nov 08, 2020 11:04 pm

Thanks so much everyone for the explanation! I was also having trouble solving this problem, but now I see what I was doing wrong.


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