Question

two thin lenses of power +3.50D and -2.5D are placed in contact. find the power and focal length of the lens combination

Answer 1

Answer:

P= 1D

F= 1m

Explanation:

The focal length of the combination of two lenses placed in contact is given by the relation.

$\frac{1}{F}=\frac{1}{f1} +\frac{1}{f2}$

→ P = P1 + P2

∴Power of combination = P = 3.5D-2.5D = 1D

Focal length of Combination = F = 1/P = 1/1 m = 1m