The intensity I of light (measured in foot-candles) varies inversely with the square of the distance from the bulb. Suppose the intensity of a 100-watt light bulb at a distance of 2 meters is 0.075 foot-candle. Determine the intensity of the bulb at a distance of 3 meters.
Here, it is given that the Intensity 'I' of light is inversely proportional to the square of the distance from the bulb
Or
or , where k is a constant
It is given that when distance is 2 meters away ,intensity is 0.075 foot candle
Substituting in the equation, we get
We need to find the intensity when the distance is 3 meters away.
Substituting the necessary variables, we get
Intensity is 0.0333334 foot candles at a distance of 3 meters away from the light bulb
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