00:01
In this problem, we are given that there is a converging mirror, which is a concave mirror, of course, and this mirror is having focal length of 20 centimeters.
00:14
And we have to determine the position where the object should be placed so that the image that's formed, it's at the same distance from this mirror as the object is.
00:26
So first, let's set the sign convention.
00:28
So we will be taking all the distance measured to the left as negative, and all the distance that we're going to measure to the right will be taking it as positive.
00:37
So let's say u is the object distance and we is the image distance.
00:41
And we are given that the distance of the object from the mirror is equal to the distance of the image from the mirror.
00:49
But here we are not given whether the image is on the right side or the left side.
00:53
So we will consider two cases.
00:55
So in the first case, we will consider the object, and the image to be formed on the same side that's on the left.
01:05
So in this case, when we use this mirror formula, we get 1 by u plus 1 by u equal to 1 by f...