The formula
is called
the Gaussian form of the thin lens formula. Another form of this
formula, the Newtonian
form, is obtained by considering the distance x from the object to
the first focal point and the distance
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Solution: Click For PDF Version In a thin lens, there are two focal points, which are located at equal distances f from the lens on either side of the lens. When a point object is located at the first focal point ,
parallel light emerges from the lens. The second
focal point
is the point where parallel light is focussed by the lens. In a
diverging lens these definitions are suitably modified.
We consider a converging thin lens. We define x the distance of the object from the first focal point as
and
In the following we rewrite the Gaussian form of the thin lens equation in two different ways:
We thus have the relation
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from the second focal point to the image.
We have to show that
.
