## Speed of Light Constant

$c=\lambda v$

mhuang 1E
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Joined: Fri Sep 29, 2017 7:05 am

### Speed of Light Constant

For the problems given in the book, the textbook uses the constant c= 2.998 x 10^8 m/s, while the module examples use 3.00 x 10^8 m/s. For the problems assigned, should we use what is given in the textbook, or what is used in the module?

Rachel Lu_dis1H
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### Re: Speed of Light Constant

I would use 2.998x10^8 to be more accurate but when you round it probably won't make a big difference. Also on the test I'm sure they'll give us the constants they'd want us to use.

Hyein Cha 2I
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### Re: Speed of Light Constant

I would use 3.00 x 10^8 for the homework problems, since Dr.Lavelle used it in his lecture~ but like the above reply said, i'm sure it will be more clear on the tests

Kyle Reidy 3H
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### Re: Speed of Light Constant

Professor Lavelle told my TA that we would be given constants on the tests. He didn't specify which ones, so I assume the speed of light will be there as well. However, just in case, this may be a good one to have memorized, since it's pretty simple.

Jana Sun 1I
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### Re: Speed of Light Constant

Would this also apply to Planck's constant? Sometimes I see 6.626*10^-34 Js but other times it's shortened to 6.63*10^-34 Js.

Joshua Hughes 1L
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### Re: Speed of Light Constant

Would this also apply to Planck's constant? Sometimes I see 6.626*10^-34 Js but other times it's shortened to 6.63*10^-34 Js.
I would use 6.626*10^-34 Js, my TA said to use that and in general, it is just more accurate. When it comes to the test I think Planck's constant should be given on our sheet, and if it is, always use whatever the sheet says because it is probably safest to be as close as possible to how the TA or teacher who is grading it will be doing it.

snehabhargava
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### Re: Speed of Light Constant

When it comes to constants, use the sig figs that are given in the problem to determine how many values past the decimal point to us in the speed of light constant or plank's constant.

Natalie LeRaybaud 1G
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### Re: Speed of Light Constant

Honestly, it doesn't really matter. You will get the correct answer either way. But it would be safer to be more exact so I would suggest using 2.998*10^8. Just remember to round to the nearest Sig Fig.

Dayanara Ruiz
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### Re: Speed of Light Constant

I would use 2.998*10^8 due to it being the one used in the textbook. Stay with the most accurate number.

Michael Lee 2I
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### Re: Speed of Light Constant

Using 2.998 x 10^8 is definitely the more accurate number. However rounding it to 3 won't cause too much of an error bound, so I don't think you would get the question wrong. But 2.998 is definitely the safe option because it is more accurate.

Camille Ng 1D
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### Re: Speed of Light Constant

Using either 3 or 2.998 on the homework doesn't really matter, just make sure you use the one that the constant sheet uses for the test.

Sophie 1I
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### Re: Speed of Light Constant

I would use 2.9988x10^8 just because it is more accurate; however, if 3.00x10^8 was the number given in the problem then I would use that one instead.

Kayla Ikemiya 1E
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### I don't know how to post my own topic

Can someone please explain how to start a new topic on this please? I also don't understand 30 C on the post module for Photoelectric effect

Jessica Wakefield 1H
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Joined: Thu Jul 27, 2017 3:00 am

### Re: Speed of Light Constant

I have been using 3.00 for the most part and it hasn't caused any error. All of my answers have been accurate and as long as you show your work on the tests/quizzes, you shouldn't lose any points for using one versus the other.

Rebecca Doan 2L
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Joined: Thu Jul 27, 2017 3:01 am

### Re: Speed of Light Constant

Since 3.00 x 10^8 m/s is the constant that Dr. Lavelle uses in lecture, I think it is safe to use that on our homework and on tests since the TAs grade them and they know what Lavelle has taught us (i.e 3.00 x 10^8 m/s).

Rebecca Doan 2L
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### Re: I don't know how to post my own topic

Kayla Ikemiya 1H wrote:Can someone please explain how to start a new topic on this please? I also don't understand 30 C on the post module for Photoelectric effect
you have to go to board index --> chem 14a --> select which topic your question pertains to and then click post a new topic

Lily Guo 1D
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### Re: Speed of Light Constant

2.998 x 10^8 m/s is more accurate, but Professor Lavelle uses 3.00 x 10^8 in his lecture slides and example problems, so I don't think using 3.00 x 10^8 would be an issue.

Glendy Gonzalez 1A
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### Re: Speed of Light Constant

I think any of these two values will be okay. Using 3.00*10^8 will only give you easier values to work with.

Steven Chau 1B
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Joined: Fri Sep 29, 2017 7:07 am

### Re: Speed of Light Constant

Any would be fine since they are relatively close enough, but I usually would use 3.00x10^8 m/s.