00:01
In this question, we have two lenses, one diverging and one converging.
00:09
So the distance between two lenses is 20 cm.
00:18
The focal length of the diverging lens is minus 10 cm and 2 is 30 cm.
00:29
And we have a 3cm tall object at the focal point of the diverging lens.
00:36
Leveraging lens, okay? so we want to find the distance of the final image relative to the converging lens and the final height of the image.
00:50
So in this question there are two lenses, so we are going to use the thin lens equation twice.
01:00
So for the diverging lens, using 1 over the o plus 1 over the i equals to 1 over f.
01:17
So we have 1 over 10 plus 1 over the i equals to negative 1 over 10.
01:26
Okay, everything is in cm.
01:28
And so 1 over di is negative 1 over 10, negative 1 over 10, minus 1 over 10.
01:35
So you have negative 1 over 5.
01:38
So the i is negative 5 cm.
01:43
So which means that the image is here, 5 cm...