What Is the frequency of red light?

AI Thread Summary
The discussion centers on calculating the frequency of red light using the speed of light and its wavelength. The speed of light is confirmed to be approximately 300,000,000 m/s, and the wavelength of red light is given as 700 nm, which converts to 0.00000070 meters. The user initially miscalculated the frequency but received guidance on proper notation and the importance of using scientific notation correctly. Clarifications were provided regarding the interpretation of the answer in different formats, emphasizing the need for precision in physics calculations. Ultimately, the user successfully solved the problem and recognized the specificity required in physics.
Daniel Kh
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Homework Statement


The speed of light in a vacuum is 3.00x(10*8)m/s. Using the equation v=fxλ, calculate the frequency of red-light. (I was told to use the wavelengths given from textbook)
Wavelength/λ =700nm

v=300,000,000 <-- ( I need help understanding this. Is this a rate? Or?)

Homework Equations


700nm = 0.00000070 meters.
^ This is what I'm confused on, do i convert this then plug it into the equation or? I'm also confused on how to plug it in.

The Attempt at a Solution


v= 3x(10*8)=300,000,000
f= 300,000,000/0.00000070=4.2857143*14 <-- I understand this is the wrong answer, however I'm terribly confused as to how to find the correct one. Even looking at examples, I don't understand what's converted and how to go about answering it.
Thank you.
 
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Hi Daniel Kh and welcome to PF.

How do you know the answer is wrong? It looks OK to me.
 
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Daniel Kh said:
v=300,000,000 <-- ( I need help understanding this. Is this a rate? Or?)
That is the speed of light. Light travels at 300,000,000 meters per second (m/s). (Actually, if I remember correctly, I think the exact speed of light is 299,792,458 m/s.) So if your answer of 4.2857143 x 10^14 is wrong, you may want to consider trying a more exact value for the speed of light.

Also, if your answer is being check by some computer system, I could see how an answer of 4.2857143*14 could be considered wrong (if that is exactly how it was entered) - unless the asterisk is interpreted by that software to be exponential notation. It reads as if you are multiplying 4.2857143 times 14.
I would have written it 4.2857143*10^14, if I was using Excel, for example. That may just be a typo on this posting, but I was just trying to think of different ways that your answer could be considered incorrect.
 
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Thanks guys!
I'm just confused on how to put that down? Do i include the power of 14? And yes, the asterick was a typo, i meant the "^".
Do I just write it has a frequency of 4.3^14?
Or should I write out the long zeroes..?
The reason I assumed it was wrong is that when i googled It, i found answers about it being something around 500Hz and that threw me off.
Should I just put 4.3 as a whole and add "Hertz" or "Hz" at the end?
Sorry for the confusion!
 
Daniel Kh said:
Do I just write it has a frequency of 4.3^14?
That is incorrect also. That is 4.28 to the 14th power.
Maybe you could try 4.28e14. That is fairly standard.

Edit: That is standard notation for 4.28 x 10^14.
 
Ah I see.
I solved It.
Thanks a ton guys! I now see Physics is very very specific.
Thanks again!
 
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