Midterm Review Q4

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tmehrazar
Posts: 39
Joined: Fri Apr 06, 2018 11:04 am

Midterm Review Q4

Postby tmehrazar » Sat May 05, 2018 9:25 am

4. a) Write an equation using words only that captures the conservation of energy in the photoelectric effect. Describe the conceptual change that arose from the photoelectric experiment and discuss how intensity plays a role.

I got the equation, but how do you describe the conceptual change and how intensity plays a role?

Anna De Schutter - 1A
Posts: 66
Joined: Wed Feb 21, 2018 3:01 am

Re: Midterm Review Q4

Postby Anna De Schutter - 1A » Sat May 05, 2018 11:25 am

Hi!

The way I answered that question is by saying that the photoelectric experiment shifted our perception from seeing light behaving only as a wave to seeing it as composed of packets of energy called photons as well. Indeed, the photoelectric experiment didn't match the wavelike properties of light because if it did, then increasing the intensity of light in the experiment should have removed electrons from the metal surface. But it didn't. This was because we were using a wavelength of light that was too short. When we decreased the wavelength, the frequency of light increased (following the equation c=lambda*frequency) and thus the energy of light increased (following the equation E=h*frequency). Thus, we started seeing light as made up of photons, and each photon of light needs to have enough energy to remove an electron. The role intensity played in the photoelectric experiment was thus to show that we can't see light as a wave anymore but as composed of photons. In this experiment, with the right wavelength of light, increasing the intensity will increase the number of electrons removed but it can't cause electrons to be removed in the first place.

I hope this helps! :)
Anna De Schutter - section 1A

tmehrazar
Posts: 39
Joined: Fri Apr 06, 2018 11:04 am

Re: Midterm Review Q4

Postby tmehrazar » Sat May 05, 2018 12:44 pm

thank you!! (: def helps


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