## Post module quiz #25

Emma Leshan 1B
Posts: 30
Joined: Fri Apr 06, 2018 11:03 am

### Post module quiz #25

25. Photoelectric experiments gave rise to a new equation relating the energy of light to its frequency. Select the right equation.

A. λv = c

B. Ek = mv2/2

C. mv2/2 = hv - φ

D. E = hv

E. None of the above

I thought the answer would be c, but it said this was wrong. Can someone please explain?

Chris Fults 1C
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Joined: Wed Nov 15, 2017 3:01 am

### Re: Post module quiz #25

Would it be A because c= the speed of light?

EllenRenskoff-1C
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Joined: Fri Apr 06, 2018 11:04 am

### Re: Post module quiz #25

I believe it would be option A because the photoelectric experiment showed that the wavelength of light is equal to the ratio of the speed of light to the frequency.

Beverly Shih 1K
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### Re: Post module quiz #25

Option A contains v (frequency of light), but c is the speed of light, not the energy of light.
Option B has to do with kinetic energy.
Option C is the equation we used in class, relating the energy of an incoming photon to the threshold energy needed to eject an electron and the resulting kinetic energy of the electron. Although this equation does include v (frequency of light) and it does have to do with energy, it has to do with threshold energy and kinetic energy of an electron, not the energy of the light source itself.
Option D: E = hv directly relates E (amount of energy per photon) to v (frequency of light) so I think the answer is D.

Mei Blundell_1J
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### Re: Post module quiz #25

I also think the answer is D, because it directly relates energy E to frequency .

Amir Akhavan 1E
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Joined: Fri Apr 06, 2018 11:01 am

### Re: Post module quiz #25

I think the answer would be choice D. The equation E= hv is the best answer because it creates a direct correlation between energy and the frequency.

Chem_Mod
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### Re: Post module quiz #25

The best answer is D because it showed quantization of energy for the photon.