what is planks constant?

Question

What is Plank's theory? What is Plank's constant h ? - from K N Swamy

Answer 1

Planck's Constant and the Energy of a Photon
In 1900, Max Planck was working on the problem of how the radiation an object emits is related to its temperature. He came up with a formula that agreed very closely with experimental data, but the formula only made sense if he assumed that the energy of a vibrating molecule was quantized--that is, it could only take on certain values. The energy would have to be proportional to the frequency of vibration, and it seemed to come in little "chunks" of the frequency multiplied by a certain constant. This constant came to be known as Planck's constant, or h, and it has the value

This doesn't make any sense to me. I think I'll go ask Dr. Mahan what J means.



That's a pretty small constant.


Yes, but it was an extremely radical idea to suggest that energy could only come in discrete lumps, even if the lumps were very small. Planck actually didn't realize how revolutionary his work was at the time; he thought he was just fudging the math to come up with the "right answer," and was convinced that someone else would come up with a better explanation for his formula.


I guess Einstein must have taken him seriously, though.


Quite seriously. Based on Planck's work, Einstein proposed that light also delivers its energy in chunks; light would then consist of little particles, or quanta, called photons, each with an energy of Planck's constant times its frequency.


In that case, the frequency of the light would make a difference in the photoelectric effect.


Exactly. Higher-frequency photons have more energy, so they should make the electrons come flying out faster; thus, switching to light with the same intensity but a higher frequency should increase the maximum kinetic energy of the emitted electrons. If you leave the frequency the same but crank up the intensity, more electrons should come out (because there are more photons to hit them), but they won't come out any faster, because each individual photon still has the same energy.


And if the frequency is low enough, then none of the photons will have enough energy to knock an electron out of an atom. So if you use really low-frequency light, you shouldn't get any electrons, no matter how high the intensity is. Whereas if you use a high frequency, you should still knock out some electrons even if the intensity is very low.


Quite right. Therefore, with a few simple measurements, the photoelectric effect would seem to be able to tell us whether light is in fact made up of particles or waves.


So did someone do the experiment? Which way did it turn out?


In 1913-1914, R.A. Millikan did a series of extremely careful experiments involving the photoelectric effect. He found that all of his results agreed exactly with Einstein's predictions about photons, not with the wave theory. Einstein actually won the Nobel Prize for his work on the photoelectric effect, not for his more famous theory of relativity.


Then light is made of particles! But wait...what about the two-slit experiment? I don't see how light could make an interference pattern like that, unless it was made of waves.


Yes, I'm afraid it's a bit more complicated than that. Some experimental results, like this one, seem to prove beyond all possible doubt that light consists of particles; others insist, just as irrefutably, that it's waves. We can only conclude that light is somehow both a wave and a particle--or that it's something else we can't quite visualize, which appears to us as one or the other depending on how we look at it.


Planck's Constant Experiment

By measuring the voltage across the LED when it just switches on and knowing the wavelength of light emitted by the LED, we can calculate Planck’s constant (h). By assuming the energy lost by an electron (qVo) when it recombines with a hole is equal to the photon energy (hf = hc/wavelength), we can write:-
qVo = hc/wavelength , or
h = qVo wavelength/c

Where c is the speed of light, q = -1.6 x 10-19

C is the charge on the electron and Vo is the threshold voltage.

Value of Planck's Constant (h) is 6.6260755 X 10-34 J s

Answer 2

there is no such thing as Planck's theory, but Planck's Law states that all matter which has temperature gives off a blackbody radiation in the eletromagnetic spectrum. Planck's Quantum hypothesis states that the energy of any molecular vibration has to be a whole number multiple of hf, or basically

E=nhf, where h is the plancks constant, f is frequency, and n=1,2,3....

this basically brought up the idea that energy is quantized, and can only exist in discrete amounts.

Planck's constant is merely a constant which has numerous uses in Quantum mechanics. The value is

6.626 x 10^-34 Js

Answer 3

Planck's constant (denoted h) is a physical constant that is used to describe the sizes of quanta. It plays a central role in the theory of quantum mechanics, and is named after Max Planck, one of the founders of quantum theory. A closely-related quantity is the reduced Planck constant. Planck's constant is also used in measuring energy emitted by light photons, such as in the equation E=hν, where E is energy, h is Planck's constant, and ν (Greek letter nu) is frequency.

Planck's constant and the reduced Planck's constant are used to describe quantization, a phenomenon occurring in subatomic particles such as electrons and photons in which certain physical properties occur in fixed amounts rather than assuming a continuous range of possible values.

The value of Planck's constant is:

h = 6.6261x10^-34 J*s, and 4.1357x10^-15 eV*s

for original paper of Planck visit:
http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Planck-1901/Planck-1901.html

Answer 4

Planck's constant is a quanta of blackbody radiation .
Blackbody is a model of Vacuum.
===============
In modern science there are two mutually exclusive points of view
on the behaviour of particles in a Vacuum. One point of view is
the position of classical physics which says that:
In the vacuum at T=0K any movement of a particle stops.
And if in the Empire of Cold there is no movement, it is a dead empire.
But another point of view completely rejects this formulation.
This point of view is expressed in the quantum theory. In 1911, M. Planck
stated that energy does not become zero at the approach T=0K.
He declared this on the 1st Solvay congress. So " Energy at T=0K" became
the main problem in physics because " Physics is first of all the vacuum".
Gradually it began to appear that Vacuum at T=0K is not empty dead space.
There live the "virtual" particles. These particles originally have negative and
imaginary mass, and then make a virtual transition " to positive mass,
becoming real particles. But the apparently mystical "virtual particles"
as they make "virtual transitions". explains little.
Let's rethink these "virtual" particles. Let's ask a question:
What is the geometrical form of "virtual" particles in the Vacuum at T=0K?
The answer is:
According to the laws of physics :
J. Charles ( 1787), Gay-Lussac ( 1802), V. Nernst ( 1910), A. Einstein ( 1925)
particles in a Vacuum cannot have volume and consequently should be flat figures.
This means, particles have the geometrical form of a circle, as from all flat figures
the circle has the most optimum form: C/D=pi.
What are these "virtual" circles in the vacuum?
The answer is given in the theory of radiation of absolute black bodies.
The theory considers an area of the space which are in absolute thermal balance.
It is possible only at T=0K. But it is known, that such a condition is a
"thermal death " and is not observed in nature. Therefore Planck, studying this area,
came to the conclusion that condition T=0K has changed. In this space there should be
a radiation of a quantum of light, possessing an internal impulse h=Et=1.
So, " the virtual circle " is transformed to quantum of light.
This quantum of light has an impulse h=Et=1 and travels with constant speed, c=1.
From this assumption Quantum theory was born.
Therefore the Quantum theory is a theory only about a quantum of light and its various transformations.
And classical theory considers all other particles.
These particles have mass much greater than a quantum of light and
move with much smaller speeds. If we understand the difference between
a quantum of light and all other particles,
then all contradictions in the physics disappear, and all of physics becomes a
harmoniously integral science.
* * *
http://www.socratus.com

Answer 5

planks constant is h = 6.63 x 10^-34

His theory was that energy comes in quantized values, packets of energy, but it's too small we don't notice it.

Answer 6

Maxwell's Equation gives: Energy= 'h'v where 'h' is the plancks constant=6.67*10^(-34) Js and 'v' is the frequency, now, c=v*wavelenght where c is speed of light , there fore, E=h*(c/wavelength) best of luck!