Question

according to Planck
E = nhv
where n is an integer (1,2,3,..) which i believe is the quanta number
h is planck constant
v is the frequency of the electromagnetic
but according to Einstein
E = hv
why there is no n?

Answer 1

Einstein's equation is \(\sf E=mc^2\)

Answer 2

i know but he also give the formula e=hv
i don't know my book is confusing.

Answer 3

but anyway my, true problem is :
please follow this link
https://books.google.com.tw/books?id=2OxrDtDaSqIC&pg=PA532&lpg=PA532&dq=an+excited+hydrogen+atom+falls+back+to+level+n+%3D+1&source=bl&ots=Bs1QOonRNA&sig=IW5zZTti_NBlI4eQ4g0XM1g72tc&hl=en&sa=X&ei=EMeGVamPDZLj8AX39IKIDQ&ved=0CB4Q6AEwAA#v=onepage&q=an%20excited%20hydrogen%20atom%20falls%20back%20to%20level%20n%20%3D%201&f=false
as we calculated the change in energy,
we undergo "e=hv" equation, what about the n?
the electron goes from sublevel 6 to 1
i am concerned about the n value, why we ignore the n value? perhaps it is 1 but why it is 1?

.

Answer 4

@abhisar

Answer 5

I am not able to access the link.

The correct formula is \(\sf E=nh\nu\), if we are talking about the energy transaction of one electron then we take n=1 but if we are taking into account energy transaction of multiple electrons, say 5 electrons then we will take n=5.

Answer 6

In your case, I believe your book is talking about one electron which goes from level 6 to 1. I think you are getting confused because we also use n to represent shell no.

Answer 7

Similarly, if we are talking about light energy. Total energy is given by the formula \(\sf E=nh\nu\) where n is the number of photons (quanta of light)

Answer 8

Is it clear now?

Answer 9

so n is just the number of electron?

Answer 10

Yes

Answer 11

hmm.. gotta need a bit time to consider this. XD

Answer 12

@Abhisar many says n is number of photons..

Answer 13

I don't want to confuse you, so just forget whatever I said above.

Answer 14

okay

Answer 15

so photons is basicly a magical thing that acts like particle but has no mass.

Answer 16

lol i am going crazy

Answer 17

The formula to find the energy of one quanta/photon is \(\sf E=h\nu\).

Now the question is when do we use \(\sf E=nh\nu\) then?

It is used to find the total energy obtained from several quanta. Remember my flour bag example?

Mass of one packet (quanta) was 1kg, if you transferred 5 packets (quanta) then total energy will be n\(\times \) 1kg = 5kg.


Similarly energy of one quanta is given by \(\sf E=h\nu\), now if someone says find the total energy if n quanta are released then we use,

\(\sf E=nh\nu\)

Answer 18

Clear?

Answer 19

makes sense but quite contradicting with what i have read.

Answer 20

anyway, thanks for helping me

Answer 21

my book says "Einstein suggested that electromagnetic radiation can be viewed as a stream of "particles" now called photons. The energy of "each" photon is given by the expression e=hv
i think the "each photon" mean n = photon...
is photon quantized?

Answer 22

i think the quanta thingy you mean is photon? is this true?

Answer 23

E=hv is used when n=1, n is just the number of photons or quanta. It's just like in the ideal gas equation how PV=nRT the n represents the number of moles. n normally just represents the number of something. So E=nhv can be used to find the amount for more than one

Answer 24

\(\color{blue}{\text{Originally Posted by}}\) @boen
my book says "Einstein suggested that electromagnetic radiation can be viewed as a stream of "particles" now called photons. The energy of "each" photon is given by the expression e=hv
i think the "each photon" mean n = photon...
is photon quantized?
\(\color{blue}{\text{End of Quote}}\)


Yes, Einstein suggested that besides the usual wave nature, light sometimes (while interacting with matter) shows particle nature and these particles are called as Photons or Quanta. These are quantized and can carry only a certain discrete amount of energy. this amount of energy is given by \(\sf E=h\nu\).

As a matter of fact you can also find the mass of these photons by using the equation \(\sf E=mc^2\)

Answer 25

@abhisar I think you mean the energy of photon can be converted into mass.. E=mc2

Answer 26

@abhisar not the photon contain mass because it is just a pack of energy??

Answer 27

Read this
http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html

Answer 28

@abhisar thank you so much, you helped me a lot.