+0

# Power Functions

0
120
4
+733

Write a power function for the following situation, and then use the equation to solve for the missing information. 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 feet from a light is 2 foot-candles, find the intensity of illumination on a screen 5 feet from the light.

AdamTaurus  Oct 18, 2017
Sort:

#1
+82809
0

Did you ask the correct queston???...we aleady know the intensity 5 feet from the light....

CPhill  Oct 18, 2017
#2
+733
0

Oh! The second 5 feet is supposed to be 15 feet.

AdamTaurus  Oct 18, 2017
#3
+82809
+1

OK.....!!!

Here's the equation we need

I  =  k / D^2   .....  and we need to find the proportionality constant, "k"....

So we have....

2  = k / 5^2

2 = k / 25       multiply both sides by 25

50  = k

And we need to solve this

I  =  50 / 15^2

I  = 50 / 225

I = 10 / 45   =   2 / 9  foot-candles

CPhill  Oct 18, 2017
edited by CPhill  Oct 18, 2017
edited by CPhill  Oct 18, 2017
#4
+733
+1

Thanks!

AdamTaurus  Oct 18, 2017

### 24 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details