Energy Levels

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Phoebe Chen 4I
Posts: 55
Joined: Fri Sep 28, 2018 12:29 am

Energy Levels

Postby Phoebe Chen 4I » Sun Oct 07, 2018 1:41 pm

I am not sure how to solve this question, it is attached as a screenshot in this post. I got the right answer by process of elimination of the multiple choice answers, but I'm wondering if there is a mathematical way to solve it.
Screen Shot 2018-10-07 at 1.10.09 PM.png

David S
Posts: 54
Joined: Fri Sep 28, 2018 12:15 am

Re: Energy Levels

Postby David S » Sun Oct 07, 2018 5:11 pm

The mathematical way is the following:

If 1 meter = 1,650,763.73 wavelengths, then divide both sides by 1,650,763.73. You should get 6.058 x 10^-7 meters = 1 wavelength.
Looking at the answers, this means that A is out the window (which intuitively makes sense).

To determine which region of the EM spectrum such a wavelength belongs to, we convert 6.058 x 10^-7 meters to 605.8 x10^-9 meters => 605.8 nano-meters.
Using some sort of reference for the EM spectrum wavelength ranges, (or recalling that professor Lavelle mentioned that visible light consists of waves with wavelengths between 400 - 700 nm) we determine that this wave must lie in the Visible light region of the EM spectrum. This makes B wrong.

To calculate the energy of a photon with a wavelength 605.8 nm with the following equation:

, h = planck's constant = 6.626x10^-34 J*s, c = speed of light = 3 x 10^8 m/s

Simply plug in the wavelength value in units of meters, and you should get 3.281x10^-19 J

I hope this helped!

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