Equations  [ENDORSED]

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Haya Rabadi 1F
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Joined: Fri Apr 06, 2018 11:04 am


Postby Haya Rabadi 1F » Sat Apr 14, 2018 9:00 pm

So when do we use the c= v x lambda equation and when do we use the E=hv equation?

Yeo Bin Yook 1K
Posts: 30
Joined: Fri Apr 06, 2018 11:05 am

Re: Equations

Postby Yeo Bin Yook 1K » Sat Apr 14, 2018 9:52 pm

E=hv can be used when finding the energy of light of a frequency or finding the frequency of a given energy of light. h is Planck's constant so it will always be 6.63x10^-34J*s.

Eduardo R 1L
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Joined: Mon Apr 09, 2018 1:38 pm

Re: Equations

Postby Eduardo R 1L » Sat Apr 14, 2018 9:59 pm

The c = v x lambda should be used when you know either know the frequency or wavelength. Because c is a constant, the unknown variable (v or lambda) can easily be solved using algebra by isolating the variable. Both equation are used in the e- ejection problems because the v in the energy equation can be replaced by c/lambda to solve for what the question may ask of you.

Eli Esagoff_1I
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Joined: Fri Apr 06, 2018 11:02 am

Re: Equations

Postby Eli Esagoff_1I » Sun Apr 15, 2018 12:03 am

I used them based on what information is given. You should almost always be given 2/3!

Adela Henry 1I
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Re: Equations

Postby Adela Henry 1I » Sun Apr 15, 2018 9:14 am

It usually depends on what information is given in the question that I use to determine what equation to use. Wavelength c=v x and E=hv for energy of light. Use both when it is the ejection of an electron.

Jose Hernandez 1D
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Joined: Tue Nov 14, 2017 3:02 am

Re: Equations  [ENDORSED]

Postby Jose Hernandez 1D » Sun Apr 15, 2018 2:42 pm

You must look at what information is given and determine which equation needs to be used.

Alondra Juarez section 1E
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Joined: Fri Sep 29, 2017 7:03 am

Re: Equations

Postby Alondra Juarez section 1E » Sun Apr 15, 2018 9:14 pm

In order to know what equation to use you would have to look at the problem and distinguish what will be needed and in some instances as seen on Friday lecture we will need to rearrange the equations in order to obtain the answer. Always check what is given in order to get to the answer.

Alma Flores 1D
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Joined: Wed Nov 08, 2017 3:01 am

Re: Equations

Postby Alma Flores 1D » Sun Apr 15, 2018 10:21 pm

It depends on the information given in the problem. Equations can be rearranged or combined to form an equation that will fit the problem. For example, E=hv can be combined with c=lambda x v, to form the equation E=hc/lambda, when you are looking for the wavelength but are not given the frequency.

Jose Munoz 1D
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Joined: Tue Nov 14, 2017 3:00 am

Re: Equations

Postby Jose Munoz 1D » Sun Apr 15, 2018 10:26 pm

Actually both can be used at the same time, the main thing is understand what each variable means, after understanding that you'll be able to see the relationships that are crossed over from both equations. The combination of the two depending on what is given in the question, can lead to the finding of frequency, energy, length,

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