Wavelength Equations
Moderators: Chem_Mod, Chem_Admin
-
- Posts: 94
- Joined: Fri Sep 24, 2021 5:37 am
-
- Posts: 63
- Joined: Fri Sep 24, 2021 6:11 am
Re: Wavelength Equations
Hi! We discussed this today in the UA session (I highly recommend going to these, they are very helpful!)
This is what he said:
Light does not have mass, objects like electrons, neutrons, protons and a baseball or a car for example all have mass, but light does not. Therefore, we can only use λ = h/p when the problem is talking specifically about an object with mass because as we've learned; momentum(p)=mass x velocity and you would need this value to find the wavelength.
Notice that λ = c/v does not have anything about mass at all, which means we would use this equation when we are talking about light specifically because as we already know, light, or a photon, does not have mass.
Hope this helps!
This is what he said:
Light does not have mass, objects like electrons, neutrons, protons and a baseball or a car for example all have mass, but light does not. Therefore, we can only use λ = h/p when the problem is talking specifically about an object with mass because as we've learned; momentum(p)=mass x velocity and you would need this value to find the wavelength.
Notice that λ = c/v does not have anything about mass at all, which means we would use this equation when we are talking about light specifically because as we already know, light, or a photon, does not have mass.
Hope this helps!
-
- Posts: 52
- Joined: Fri Sep 24, 2021 6:25 am
Re: Wavelength Equations
It really depends on the subject you are calculating and if it has a mass or not.
Since λ = h/p has a component of momentum(p) which equals to p = mv, thus only when you are calculating something that has a mass you can use this function. However, when calculating the wavelength of light related subjects like photon, you should go with λ = c/v which has nothing to do with mass.
Since λ = h/p has a component of momentum(p) which equals to p = mv, thus only when you are calculating something that has a mass you can use this function. However, when calculating the wavelength of light related subjects like photon, you should go with λ = c/v which has nothing to do with mass.
-
- Posts: 102
- Joined: Fri Sep 24, 2021 5:48 am
Re: Wavelength Equations
The "p" in λ = h/p is momentum which is equal to mass times velocity. So when you are given mass you use this formula.
You use λ = c/v when you are not given a mass.
You use λ = c/v when you are not given a mass.
-
- Posts: 77
- Joined: Fri Sep 24, 2021 6:43 am
Re: Wavelength Equations
Hi,
Both equations work in different scenarios. it depends on all of the knowns in the question asked. If frequency is given and you need to find wavelength, then c=lamda*V would work. Same goes for the other equation. It is all dependent on what you are given in the problem. When you have a mass, it is necessary to use lambda = h/p.
Both equations work in different scenarios. it depends on all of the knowns in the question asked. If frequency is given and you need to find wavelength, then c=lamda*V would work. Same goes for the other equation. It is all dependent on what you are given in the problem. When you have a mass, it is necessary to use lambda = h/p.
Return to “Properties of Light”
Who is online
Users browsing this forum: No registered users and 8 guests