Question

The intensity of light measured in foot-candles varies inversely with the square of the distance from the light source. Suppose the intensity of a light bulb is 0.08 foot-candles at a distance of 3 meters. Find the intensity level at 8 meters.

Answer 1

Answer:

0.01125 foot-candles

Step-by-step explanation:

According to the data,  intensity of light measured in foot-candles varies inversely with the square of the distance from the light source

Therefore,

$I$ α 1/$d^{2}$

$I$ = k/ $d^{2}$

where,

'k' is the constant

'd' is the distance from bulb

'$I$ ' is intensity of a light bulb

When,

d= 3meters

$I$ = 0.08foot-candles

k= $I$ .  $d^{2}$

k=  0.08 x 3² => 0.08 x 9

k= 0.72

Next is to determine the intensity level at 8 meters.

$I$ = k/ $d^{2}$

$I$ = 0.72/ 8²

$I$ = 0.01125 foot-candles

Therefore, the intensity level at 8 meters is 0.01125 foot-candles