Question

Two lenses have powers +2D and -3D respectively. The power of combination is :
1: -1 D
2: +2 D
3: +1 D
4: +3 D​

Answer 1

Given ,

The power of two lenses are + 2D and - 3D

We know that ,

The power of lens is defined as the ability of lens to converge or diverge a light rays falling on it

The equivalent power of lenses incontact is given by

$\large \sf \fbox{P = P_{1} + P_{2} + ... + P_{n}}$

Thus ,

P = 2 + (-3)

P = -1 D

$\therefore\sf \underline{The \: equivalent \: power \: of \: two \: lenses \: incontact \: is -1 \: D}$