When two or more lenses are placed in contact, what will be their combined power?
When two or more lenses each of power P1, P2, P3, P4… Pn . are placed in contact with each other as shown in the figure below.
Then the combined power of the combination is the sum of all individual powers.
⇒ P = P1 + P2 + P3 + P4 + …..+ Pn