00:01
Hello, hello students.
00:02
So in that numerical, this is a concave lens.
00:06
So first of all, we write here that is a concave lens.
00:10
And he says that the focal length of that concave lens is a, so focal length of a concave is considered in a negative.
00:17
So we are considered a minus of a 15 centimeter.
00:21
He wants to say what is the position of object if we want to, the image will be formed at a minus of a 10 cm.
00:30
Why we are considered a negative sign due to that condition.
00:34
Let's see.
00:35
This is your lens, guys.
00:36
Okay, if you are placed, that is a, this is your direction of incident.
00:41
So it is positive and negative...