SOLUTION: The intensity of light varies inversely as the square of the distance from its source. How much farther from the light must an object moved to received one-half the amount of light

Algebra ->  Expressions-with-variables -> SOLUTION: The intensity of light varies inversely as the square of the distance from its source. How much farther from the light must an object moved to received one-half the amount of light      Log On


   

Question 1087617: The intensity of light varies inversely as the square of the distance from its source. How much farther from the light must an object moved to received one-half the amount of light it now received if it is placed 2 ft from the source of light?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = distance from source
Let +I+ = the intensity of the light
------------------------------------
+I+=+k%2A%28+1%2Fd%5E2+%29+
+d+=+2+ ft
+I+=+k%2A%28+1%2F4+%29+
+k+=+4I+
-------------------
What if intensity is +I%2F2+ ?
+I%2F2+=+k%2A%28+1%2Fd%5E2+%29+
+I%2F2+=+4I%2A%28+1%2Fd%5E2+%29+
+1%2F2+=+4%2A%28+1%2Fd%5E2+%29+
+d%5E2+=+8+
+d+=+2%2Asqrt%282%29+
---------------------
+2%2Asqrt%282%29+-+2+=+2%2A%28+sqrt%282%29+-+1+%29+ ft
This is how much further away the object has to be moved from the light
Definitely get a 2nd opinion