Question

Two lenses of +2D and 3D are placed in contact with each other. What is the power of
resulting lens? What is the focal length? Will the combination behave like a convex or a
concave lens
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Answer 1

Explanation:

Pnet = 2+3 = 5D

focal length = 1/Pnet =1/5 =0.2m or 20cm

since the focal length is positive, the combination will behave like a concave lens