00:01
Okay, so we're doing chapter 32, problem 16.
00:05
So what this is identis wants a small mirror that went in two centimeters from the tooth, so obfuscant's two centimeters, produces a four times a bright image.
00:17
So m equals four.
00:20
So what kind of mirror must be used and what must its radius of curvature be? well, immediately, we should know that the only way we can get upright magnified images with a concave meter.
00:38
But first, let's figure out what the focal length and radius of correction will be.
00:42
So we know from the magnification formula that this is negative d -i over d -0.
00:49
So if we solve this, we can say d -i equals negative m -d -o for the object distance.
00:55
So now using our optics equation, one over object distance, plus 1 over the image distance.
01:04
It's 1 over the focal length.
01:06
We solve for focal length.
01:09
This is d0, d0, or times di over d not plus di.
01:17
Let's substitute in our expression for di...