Problem about application of E = hv to white light

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Discussion Overview

The discussion revolves around the application of the equation E = hv to the phenomenon of white light emitted by a light bulb. Participants explore the implications of this equation in the context of light emission and perception, questioning how multiple frequencies can coexist in what is perceived as white light.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that if E = hv applies, then a light source emitting a constant energy should only produce one frequency of light, leading to confusion about the nature of white light.
  • Another participant argues that the perception of white light arises from the presence of multiple photon energies, which are detected by different receptors in the human eye.
  • A third participant clarifies that a typical light bulb emits a wide range of frequencies, and E = hv applies to individual photons rather than the collective output of the bulb.
  • There is a humorous acknowledgment of the complexity of the situation, emphasizing the misunderstanding of applying E = hv to the concept of white light.

Areas of Agreement / Disagreement

Participants express differing views on the application of E = hv to white light, with some clarifying the limitations of the equation in this context. There is no consensus reached regarding the initial misunderstanding of the equation's implications.

Contextual Notes

The discussion highlights the need for clarity regarding the definitions of energy and frequency in relation to light emission, as well as the distinction between individual photons and the collective perception of light.

Who May Find This Useful

Individuals interested in the physics of light, particularly those exploring the relationship between energy, frequency, and human perception of color.

Zynoakib
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The reason why we see white light is because we see all the light in the visible lights spectrum.

So let's say I have a light bulb that gives out white light, the reason why it gives out light its because it keeps emitting a constant amount of energy. By E = hv, we should only be able to see one kind of light. ( for instance, the energy emitted by light is 100 J and the frequency of the light wave should be 100/h, which means one kind of light) So why can we still see white light?

What is wrong with my concept? Thanks a lot!
 
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Zynoakib said:
By E = hv, we should only be able to see one kind of light. ( for instance, the energy emitted by light is 100 J and the frequency of the light wave should be 100/h, which means one kind of light) So why can we still see white light?

You logic for that conclusion escapes me.

The reason we see white light is we have receptors for many different photon energies and when they are all present we perceive that as white.

Thanks
Bill
 
A 100 watt light bulb radiates 100 Joules per second in a wide range of frequencies, only some of which are in the visible part of the spectrum. So in 1 second 100 Joules of photons are emitted in many colors. E=hv gives the energy of just *one* photon, and v=E/h its color. Since, there is no such thing as a white photon you cannot use use v = E/h this way. Using the formula for v with E = 100 Joules would only make sense, for example, if the 100 watt bulb radiated just one 100 Joule photon per second. And that would not be white light!
 
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James_Harford said:
Using the formula for v with E = 100 Joules would only make sense, for example, if the 100 watt bulb radiated just one 100 Joule photon per second. And that would not be white light!

This made me laugh :-P I mean, it's true of course, but my God is it an understatement.
 
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