a thin double convex lens is cut into two equal pieces A and B by a plane containing the principle axis.If the focal power of the original lens is P then those of A and C are respectively.
Answers
Answer:
Focal power is P of both the lenses.
Explanation:
Cutting the lenses along principal axis doesn't affects their focal length at all and hence their is no change in focal power. However, the intensity of image formed by the lenses produced by cutting original one is reduced. It is equivalent to covering the half part of lens.
The Power of lens A is P and the power of lens C is P/2.
Given,
The focal power of the initial lens is P.
To Find,
Power of A and C at last.
Solution,
We can solve this type of problem by the Ray Optics concept:
Now,
According to ray optics power of a lens is inversely proportional to its focal length. Thus, a short focal length lens has more power, whereas a lens of long focal length has less power.
So Lens, A focal length will not change after cutting in two halve then the focal length, = f
The focal length of C = 2f
Power of lens A is Pa = P
The power of lens C is Pc = 1/2f = P/2
Hence, the Power of lens A is P and the power of lens C is P/2.
