Power source of radiation

  • Thread starter jasmin_89
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  • #1
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Homework Statement:

Power source of radiation

Relevant Equations:

Is my solution correct?
Hallo, can anybody help me and check if i have the right result:

What is the minimum power P that a point source of radiation (I=8*10^(-7) W/m^2) at a distance of l=10 m from the listener must have in order to still be perceived? (Note: The emitted energy per area can be related to a spherical body with A=4 π r^2)

P=I*A
P=8*10^-7 (W/m^2)*4*pi *(10m)^2= 0,001 Watt
 

Answers and Replies

  • #2
Filip Larsen
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:welcome:

Your result looks correct to me.

Small nitpick: If no other constraints are given I would probably write the result as 1.0⋅10-3 W or just 1.0 mW to better signal the number of significant digits in the result.
 
  • #3
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Ok, thank you :)
 
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