The focal length of the bi-convex lens (f) can be calculated as follows:
f1==(μ−1)(R1−−R1)R2(μ−1)...(1)
When the lens is cut into two halves, the focal length (f′) of each part can be calculated as follows:
f′1==(μ−1)(R1−∞1)R(μ−1)...(2)
Hence, the ratio of the powers for both the lenses can be given by
PP′====⇒f1f′1f′fR2(μ−1)R(μ−1)21P′=2P...(3)
Substitute the value of the known parameter into equation (3) to calculate the required power.
P′==210D5D