00:01
Okay, in this problem we have a mirror, a spherical mirror of some kind, with a focal length f that we know and a magnification m that we know so for part a we're asked to show that the object distance is equal to the focal length times one minus over 1 over m this expression and then we're asked to demonstrate for a convex mirror that the magnification is always between zero and one so it starts out we're going to be making use of two things one the definition of magnification.
00:30
Yes, it's the ratio of heights and for the image and object respectively, but it's also the negative ratio of distances for the image and object.
00:39
So we make use of that.
00:40
We're also going to use the ideal lens equation.
00:43
1 over f is equal to 1 over d0, or d0, or d0 rather, plus 1 over d .i.
00:49
Make use of these two things.
00:52
So it starts off for part a.
00:55
Take our definition of m, which is equal to negative d .o, which gives us an expression for d .i.
01:05
In terms of the other quantities that we know.
01:09
It's negative m, d, o...