Physics
A lens of power +2.5D is kept in contact with another lens of power -2.5D. What will be the power of the combination of the two lenses? How will the combination behave?
Answer
Given, P1 = +2.5D and
P2 = -2.5D
We know P = P1 + P2
Substituting we get, P = +2.5 + (-2.5) = 0
Hence, the power of the combination of these two lenses is 0 D. This means that the combination behaves like a piece of plain glass. When light passes through this combination, it will not converge or diverge; it will simply pass straight through without being affected by refraction.
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