00:02
So we're going to discuss how to change how we're going to find different intensity levels of different sounds.
00:10
And this is the formula that we're going to use.
00:14
And for this formula, we're going to use that i .0, the original intensity, is 10 to the negative 12.
00:21
And that's about the softest sound that an average human air can, that a human can hear.
00:27
So we're going to try to find out different sound levels.
00:30
Like this is the intensity of a jet.
00:35
So different intensities, we're going to find out what i is.
00:39
So for this one, we're going to say b equals 10 times the log.
00:45
Now, we have 10 to the negative 11 on top, but on the bottom, we're going to use 10 to the negative 12.
00:53
And one skill that we have to remember is when we have the same base and we need to combine them, we're going to subtract exponents.
01:01
So in here i really have 10 to the negative 11 minus negative 12.
01:07
Lots of students mess up that minus negative 12.
01:11
That gives us 10 to the negative 11 plus 12, 10 to the 1.
01:16
Now on this one i want to show you something.
01:19
10 times the log of 10.
01:22
Remember, that's a common log.
01:25
So 10 base 10 is really 10 to the what equals 10.
01:33
So i know x equals 1.
01:37
Because this is really this.
01:41
We can also remember a shortcut.
01:43
It's always how many zeros we have with this on top...