Question

I need help. PLEASEEE?????

Answer 1

Physics
For a 225-Watt bulb, the intensity I of light in lumens at a distance of x feet is I = 225/x^2.
a. What is the intensity of light 5 ft from the bulb?
b. Suppose your distance from bulb doubles. How does the intensity of the light change? Explain.

Answer 2

@TuringTest

Answer 3

@electrokid

Answer 4

considering the light bulb to be a point source, the light is dispersed in all directions. hence, the points with same power or intensity form a sphere.

Total power of the bulb is spead over the entire surface area of the cube.
Intensity of light = power per unit area

Answer 5

that is why you have that equation.
\[I={P\over x^2}\]
plug in the value for P and x and calculate I

Answer 6

for part b, the question says, that "x" gets doubled. what do you think will happen?

Answer 7

x ^2

Answer 8

How can i find x?

Answer 9

read the question. it tells you what "x" is

Answer 10

5 ft?

Answer 11

yep

Answer 12

When it says x doubles, do i have to do x squared?

Answer 13

yes
but what will be "x"?

Answer 14

for part a I = 225/5 or I=225/5^2

Answer 15

you know the answer for that.

Answer 16

is it I=225/5^2 which equals 9

Answer 17

good.

Answer 18

ok, and for part b how can i do it? so x is 25, does that mean i should double it?

Answer 19

"x" is what?

Answer 20

25. because x^2 and x was 5

Answer 21

"x" is still "5"

Answer 22

\(x^2=25\) and \(x=5\) are two different things.

Answer 23

ok

Answer 24

If you got 5 bucks and your uncle doubled it, how much would you have?

Answer 25

10 lol

Answer 26

so it will be I=225/10^2

Answer 27

bingo

Answer 28

ok thank you very much @electrokid !

Answer 29

yw :)