Measuring Intensity of Sources of Light

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Discussion Overview

The discussion focuses on methods for measuring the intensities of various light sources, such as candlelight and tungsten filament bulbs. It explores the definitions of intensity and related concepts, as well as practical measurement techniques.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about measuring the intensities of different light sources.
  • Another participant suggests that a setup requires a light-directing mechanism and a sensor to convert light into electricity.
  • A third participant provides definitions for intensity, irradiance, and radiant emittance, questioning which specific measurement the original poster intends to pursue.
  • A later reply challenges the terminology used by the third participant, suggesting that "radiant intensity" would be a more appropriate term for W/sr to avoid confusion with the common use of "intensity" in physics.

Areas of Agreement / Disagreement

There is no consensus on the definitions of intensity and related terms, as participants express differing views on terminology and measurement focus.

Contextual Notes

Participants highlight the need for clarity in definitions and measurement goals, indicating potential confusion in terminology and the importance of specifying what is being measured.

shaddy
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how do i measure the intensities of different sources of light?
eg. candle light, tungsten filament etc.
 
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You must have at least two things : first, something that can direct light from the source to the cell and secondly the cell (sensor) that can convert light into electricity.
The 1st part can be made very simply as a narrow tube which is long enough so the sensor can only receive light from the source.
 
Be careful with your quantities here.

Intensity = W/sr
Irradiance = W/m^2 (at the observer)
Radiant Emittance = W/m^2 (at the source)

Which specifically do you want to measure (I'm guessing Irradiance).

Claude.
 
Claude, that's an unusual set of definitions, you should consider calling W/sr "radiant intensity" to distinguish it from the notion of "intensity" that is normally used in at least early undergraduate physics.
 

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