Question

If the distance from a light source triples, how does light intensity change? The intensity will be 3x greater. The intensity will be 1/3 as much. The intensity will be 1/9 as much. The intensity will not change.

Answer 1

The intensity will be 1/9 as much.

Step-by-step explanation:

The intensity of the light or any source is inversely related to the square of the distance.

`I\alpha (1)/(r^(2) )`

Now according to the question the distance is increased by three times than,

`(I_(2) )/(I_(1) )=(r_(1)^(2) )/(r_(2)^(2) )`

Therefore,

`(I_(2) )/(I_(1) )=(r_(1)^(2) )/((3r_(1))^(2) )\\(I_(2) )/(I_(1) )=(1)/(9) \\{I_(2)=(1)/(9){I_(1) }`

Therefore the intensity will become 1/9 times to the initial intensity.