Many physical quantities are connected by inverse square laws,that is,by power functions of the form In particular,the illumination of an object by a light source is inversely proportional to the square of the distance from the source.Suppose that after dark you are in a room with just one lamp and you are trying to read a book.The light is too dim and so you move the distance to the lamp.How much brighter is the light?
A) times
B) times
C) times
D) times
E) times

Question

Many physical quantities are connected by inverse square laws,that is,by power functions of the form  In particular,the illumination of an object by a light source is inversely proportional to the square of the distance from the source.Suppose that after dark you are in a room with just one lamp and you are trying to read a book.The light is too dim and so you move  the distance to the lamp.How much brighter is the light?
A) times 
B) times 
C) times 
D) times 
E) times

Quizplus · Accepted Answer

The illumination of an object by a light source is inversely proportional to the square of the distance from the source. Therefore, if you move twice as far away from the lamp, the illumination is divided by 2^2 = 4. In this case, you move 3 times as far away, so the illumination is divided by 3^2 = 9. Therefore, the light is 9 times dimmer or 1/9th as bright, so the answer is C.

Many Physical Quantities Are Connected by Inverse Square Laws,that Is,by