00:01
Hello students, according to the given question we have a microscope of focal length 4 .1 mm and the magnification of this objective is minus 2 .9.
00:20
Now we have to find the objective distance.
00:30
Before this try to draw the diagram of this microscope.
00:41
This one is our objective.
00:48
This is eyepiece.
00:50
This is the object distance for objective u.
01:06
I try to draw the ray diagram so that you clearly understand.
01:12
And this is our image distance of objective and this image distance or this image of this first object is we have as a object for our eyepiece.
01:43
This is the final u.
01:51
Now we have to first find the object distance of this objective.
02:01
How we can find that? we have a magnification minus 2 .9.
02:06
We know the magnification formula m is equal to f upon f plus u where f is the focal distance and u is the object distance.
02:20
Let me explain more about this formula.
02:25
You know the lens formula 1 by v minus 1 by u is equal to 1 by f multiply both sides by u.
02:36
U by v minus 1 u by f.
02:39
This is the inverse of magnification into u by f.
02:45
From here we get the magnification is equal to f upon u plus f.
02:52
Now put the value here minus minus m is equal to minus 2 .9 is equal to f...