00:03
In this problem we have a projector that we use to form the image of this object.
00:12
That is a slide on the other size of the lens.
00:19
And we know the size of the width of this slide and of the image that it produced.
00:31
We also know that the distance between the lens and the image is 3 .5 mirrors and we want to compute what is the focal length of the lens.
00:44
Well, in order to compute the focal length, we need the object distance and the image distance.
00:51
Now we have the image distance, 3 .5 mirrors is the image distance, as it is the distance between the lens and the image.
01:02
But we need the object distance that is what we use to call p.
01:09
And it's this value here.
01:11
In order to compute p, we can use this relation that is related with a magnification.
01:22
We know that the ratio between the values of w prime and w is minus q over p.
01:32
From this, we can compute the value of p.
01:39
But before of that, we must to take care with these numbers here, because we know that this converged lens produce images that are inverted for respect to the object...