## Hw Question 1A.9

$c=\lambda v$

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Maya Pakulski 1D
Posts: 105
Joined: Thu Jul 11, 2019 12:17 am

### Hw Question 1A.9

For the question 1A.9, how would you find the the wavelength and frequency that go along with the second line that says 3.3X10^-19J?

Sharon Rodriguez 3H
Posts: 50
Joined: Wed Nov 14, 2018 12:18 am

### Re: Hw Question 1A.9

You know the energy of the photon (E) and we know E=hv with h being Planck's constant (6.626x10^-34 J.s) so the only unknown in this equation would be v, the frequency. Rearange the equation to solve for v which would be v=E/h. After plugging in the values and finding the answer, you can find the wavelength (λ). We know λ=c/v with c being the speed of light (3.00x10^8m.s^-1) and v being the value you just found. Plug in and you've got your value for λ. Hope this could help!

Ashley Nguyen 2L
Posts: 103
Joined: Sat Aug 17, 2019 12:18 am
Been upvoted: 1 time

### Re: Hw Question 1A.9

To find the wavelength and frequency of the photon in this question, it is best to start from what you know. You know the energy of the photon, so the only equation we can use in this instance would be E(photon) = vh, where v is the frequency in Hertz and h is Planck's constant. Rearrange the equation so you can solve for the only other unknown in the equation, which is v, the frequency. After solving v = h/E, you have enough information to plug into the last equation, c = λv, where the product of wavelength and frequency is indirectly proportional to the speed of light c. Rearrange this last equation to solve for λ, wavelength. After solving for λ, you can correctly determine which event is occurring.

DesireBrown1J
Posts: 98
Joined: Wed Sep 18, 2019 12:18 am

### Re: Hw Question 1A.9

For this homework problem, the given wavelength is in nm. Should we covert all the wavelengths we need to find to nm? We are also given two different frequencies, one in Hz and one in MHz. Should the answers for the other two frequencies be in Hz or MHz?

LReedy_3I
Posts: 51
Joined: Fri Aug 30, 2019 12:17 am

### Re: Hw Question 1A.9

All of the information for this problem can be found using E = hv and λv = c. First, find the frequency using E = hv, by plugging in planck's constant and 3.3x10^-19 J for E. This gives the frequency as 5.0x10^14Hz, which can then be plugged into λv=c to find the wavelength (600nm).

Sarah Nichols 4C
Posts: 52
Joined: Sat Aug 24, 2019 12:18 am

### Re: Hw Question 1A.9

For the line with the frequency listed as 300MHz, I converted to Hz and got 3.00x10^8 Hz, but then using wavelength=c/frequency you would get a wavelength of 1m, which doesn't make sense for the "events" context of this question. Not sure what part I'm doing wrong?

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