Flux vs Power Query - Explained

  • Context: Undergrad 
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    Flux Power
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Discussion Overview

The discussion centers around the relationship between flux and power, particularly in the context of photons emitted from a light bulb. Participants explore the definitions and implications of these concepts, questioning how flux, defined as the amount flowing through per unit area per unit time, relates to power, which is energy per unit time.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant defines flux as the amount that flows through per unit area per unit time and questions why the flux from a light bulb is equal to power.
  • Another participant explains that energy is related to the number of photons, providing the equation for the energy of photons (E = hf) to support their point.
  • A different participant raises a concern about the area aspect of flux, suggesting that the dimensions may not align correctly with the definitions provided.
  • One participant clarifies that flux can be expressed in different contexts, such as per area, per solid angle, or as total flux, indicating the importance of context in understanding the terms.

Areas of Agreement / Disagreement

The discussion features multiple viewpoints, with some participants agreeing on the relationship between energy and photons, while others express uncertainty regarding the dimensional consistency of flux and power. The discussion remains unresolved regarding the precise relationship and definitions.

Contextual Notes

Participants have not fully addressed the implications of area in the definition of flux, nor have they resolved the dimensional concerns raised. The discussion relies on contextual interpretations of flux.

lavster
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Hi,

my understanding of flux is that it is the amount that flows through per unit area per unit time. with this in mind, why is the flux (of photons I am assuming) from a light bulb equal to the power, which is the energy per unit time?

Thanks
 
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Because energy is directly related to the number of photons. The energy of one photon is E(of one photon) = hf. So for 2 photons, E(of 2 photons) = 2hf, and so on. (f is the frequency of the photon)

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thanks :) however it says nothing about the area? is it not meant to b per unit area? so the dimensions are wrong?
 
You can have flux per area, flux per solid angle, and total flux. You really have to look at the context to figure out which one it is.
 

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