00:01
For part a, they are just asking us to calculate what is the equation or to find the formula.
00:07
And they say that the intensity of light is inversely proportional to the distance.
00:14
Inversely proportional means if i is on the numerator on this side of the equation, the squared of the distance is going to be on the denominator on the other side of the equation.
00:24
What we have on the numerator here is a constant.
00:27
It's just a given constant.
00:29
This is how we write inversely proportionate relationships.
00:33
If they were directly proportional just for the sake of understanding, then it would be k times d squared.
00:41
But we have inversely proportional, so that's why we do division.
00:46
Now, what we do is we use the information given to find k.
00:50
We are given the i to be six locks, and the distance to be 30.
00:59
Meters.
01:00
So if i is six and this 30 that's what we do.
01:04
We replace them six is equal to k over 30 squared.
01:11
But 30 squared is the same as 900.
01:15
What we do now is we solve for k multiplying both sides times 900 times 900 and times 900 the nine hundreds cancel on the right leaving us that that k or the constant k is equal to 5 ,400, and the units would be just looks times meters squared...