Inverse Square Law concerning Light

AI Thread Summary
The discussion focuses on how the distance from a point light source affects light visibility, emphasizing the Inverse Square Law (ISL). The formula I1 x d12 = I2 x d22 is used to calculate light intensity at various distances. The poster plans to measure intensity at intervals using a voltmeter and a CdS cell for verification. There is a clarification regarding terminology, where "visibility" is corrected to "intensity," and the term "irradiance" is introduced as the appropriate measure of power per area. The conversation highlights the importance of precise definitions in understanding light intensity and its variation with distance.
MangoOverlord
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[a]1. Homework Statement [/b]
How does the distance from a point source of light affect the visibility of that light from the said source?


Homework Equations


This is a bit tricky without sub points, but here goes:

I1 x d12=I2 x d22
where:
I=intensity d2=distance per sq. unit

[c]3. The Attempt at a Solution [/b]

By using the ISL formula above, I plan to find the intensity of light at predefined intervals (i.e. every 10 cm) by substituting variables in the equation. After which, I will use a voltmeter and CdS cell to verify my calculations. I'm pretty sure I'm doing everything right, but some suggestions would be nice. :biggrin:
 
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You might want to be careful defining "visibility"
What you are measuring is how the power received by a fixed area (the lightmeter) = the irradiance of the light varies with distance.
 
did i say visibility? I meant intensity. Ty.
 
MangoOverlord said:
I meant intensity. Ty.
intensity is the power of the source
the correct term is irradiance = power/area
 

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