My Math Forum  

Go Back   My Math Forum > High School Math Forum > Elementary Math

Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion


Reply
 
LinkBack Thread Tools Display Modes
January 16th, 2011, 08:20 AM   #1
Newbie
 
Joined: Jan 2011

Posts: 1
Thanks: 0

How does the inverse square law of light effect light intens

Hi,

OK. I now know how to work out the "dose" of red light treatment based on this formula:

(unit is a 633nm red LED unit - 70 mW/cm2)

So to work out the J/cm2 for on minute it is- (70x60)/1000 = 4.2 J/cm2

I guess this is based on the assumption that no light is lost from the illuminated area (so the diode is pretty much as close to the skin as possible) and doesn't take into account the lack of uniformity of LEDs.

Anyway....so lets just say for argument that the distance is 1/2 inch. Am I right in assuming that if the distance is doubled to 1 inch, the result will be 4x less powerful, so around 1 J/cm2 per minute?

______________________________________

PS - I saw this on the article I was reading which I don't understand as well: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2790317/

Energy (J) or energy density (J/cm2) is often used as an important descriptor of LLLT (low level light treatment) dose, but this neglects the fact that energy has two components, power and time, and it has been demonstrated that there is not necessarily reciprocity between them; in other words, if the power doubled and the time is halved then the same energy is delivered but a different biological response is often observed.
moore778899 is offline  
 
Reply

  My Math Forum > High School Math Forum > Elementary Math

Tags
effect, intens, inverse, law, light, square



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Light Reflection Problem 4GB-FLASH-DRIVE Algebra 1 March 2nd, 2013 02:44 PM
Can someone shed light on this? sivela Calculus 2 March 18th, 2012 04:46 PM
Frames of reference and the speed of light proglote Physics 23 August 26th, 2011 07:01 AM
CAN SOMEONE SHED SOME LIGHT ON THIS PROBLEM Nazz Advanced Statistics 1 July 15th, 2008 10:26 PM
Light Switches mahuirong Algebra 9 January 1st, 2008 01:30 PM





Copyright © 2018 My Math Forum. All rights reserved.