P-l-a-n-k (1 Viewer)

[rosygirls92]

Hey all just a quickie

Identify Planck’s hypothesis that allowed him to successfully predict the black body​

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radiation curve.​

Energy is exchanged between the walls of the black body and
the nearby space in discrete, not continuous, bits of energy​

called “quanta”.
That's the answer, but i don't understand it, could someone clarify?

 

[xFusion]

plancks hypothesis "an atom could only be given energy in a specific whole number(quanta)" this means that an atom can only absorb a certain amount of energy which meant decreasing wavelengths did not always mean increasing intensity (ultraviolet catastrophe).

 

[anom1ly]

Hey all just a quickie

Identify Planck’s hypothesis that allowed him to successfully predict the black body​

radiation curve.​

Energy is exchanged between the walls of the black body and
the nearby space in discrete, not continuous, bits of energy​

called “quanta”.
That's the answer, but i don't understand it, could someone clarify?

what this means is, that when light rays hit the walls of a black body, its energy isn't transferred to the electrons continuously, but rather in little bursts of energy.
picture light as little balls (quanta). each ball has energy given by the equation e=hf. so the energy within light exists within these little quanta, and thats how light is transferred into the lattice of a blackbody, rather than classical physics explanation, that it was a continuous beam being absorbed by the blackbody.

 

[MrWatts]

You don't have to understand it because it says "identify"... That's the trouble with the current syllabus, it doesn't try to teach you physics or assess your "understanding" it just introduces you to topics that are 2nd and 3rd year university concepts in a dumbed-down manner... but, yeah, it's something to do with quantum.

 

[Toranilor]

As far as I'm aware, the explanation went like this;

Firstly, Plank established that the energy cost of making a specific frequency of light increased exponentially as frequency increased. This can be explined in two ways;
- Plank's equation, E = hf, could also be written E = hc/λ. (as f = c/λ) As 'c' is constant, when λ -> 0, (frequency increases), E -> ∞

- If one viewed the atom as an antennae, the frequency of the photon could be seen as an inverse function of the speed of the electron (as work function and mass are constant in this secnario, all excess energy imparted to the electron would be converted into kinetic energy). Therefore, for frequency to increase past a certain point, the electron has to approach relativistic speeds, where the energy cost for a speed increase rises exponentially.

As such, by establishing the exponential growth of energy cost, plank hypothesised that, when the predominant frequency of the black body shifted past a certain point, the energy cost to make that frequency outstripped the energy from the increase of heat of the black body. (Increasing the heat shifts the predominant freuqency). As such, the graph would peak and then decline, as the total intensity of the light decreased past that critical point.

Then again, I could be wrong. Consult a physics authority.