00:01
Hi everyone as shown in the figure there is a thin glass lens of refractive index 1 .5 and having radii of curvature r1 2b 15 cm and r2 minus 12 cm to the left of the lens there is a cube having the face area the face area of tube is given 100 centimeters square the base of the cube is on the axis of the lens and right face is 20 centimeter to the left as soon in the figure in the first case we have to find the focal length of the lens and we have to draw image of a square face draw image of square face see part determine the area of image area of image let us start solving the first part.
01:28
Focal length of the length is measured by the formula 1 upon f is called 2 n minus 1 1, r1 minus 1 upon r2 that is 1 .5 minus 1 into 1 upon 15 minus 1 upon 12.
02:11
So focal length you will get 13 .3 cm this is the answer of a part.
02:21
Now we have to discuss the answer of b part.
02:24
We have to draw the ray diagram.
02:27
Let us see here.
02:29
I will try to draw it but let us see.
02:36
This is the lens thin lens i am showing here.
02:48
This is the face of the cube.
02:53
Take ray of light from here and here from both the corners.
02:59
Palleled to the principal axis.
03:02
It gets converse through the focus point...