SOLUTION: The intensity I of light varies inversely as the sqaure of the distance D from the source. If the intensity of illumination on a screen 5ft from a light is 4 foot candles, find the

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Question 797491: The intensity I of light varies inversely as the sqaure of the distance D from the source. If the intensity of illumination on a screen 5ft from a light is 4 foot candles, find the intensity on a screen 20ft from the light.

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Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The intensity I of light varies inversely as the square of the distance D from the source.
If the intensity of illumination on a screen 5 ft from a light is 4 foot candles,
let k = constant, then I = k%2FD%5E2
Find K
k%2F5%5E2 = 4
k = 25*4
k = 100
:
find the intensity on a screen 20ft from the light.
I = 100%2F20%5E2
I = 100%2F400
I = 1%2F4 foot candle