00:01
So if we start with a concave mirror here that has a candle in it, i'm just going to draw the candle as an arrow here.
00:13
And we are told that the magnification of this image that is produced is negative .75, and it forms an image that is 4 .6 centimeters away.
00:26
All right.
00:28
So we already know a few things from just the magnification.
00:30
The fact that it's negative means that the image is inverted.
00:38
And since it's a number less than one, we know that the image is reduced.
00:44
And every time you have a inverted image, it will be real, right? which means q really is positive and appears on the same side of the mirror as the object.
00:56
So given those two things, i'm going to use.
00:59
The magnification formula to solve for the object distance and then we can use that to solve for the focal length.
01:09
Right.
01:10
So it's negative 4 .6 over p is negative 0 .75 and so the negative signs cancel and so p is going to be 4 .6 divided by 0 .75 right? so you can plug that into a calculator if you wanted.
01:40
Right...