Answer: -0.5 D
Explanation:
The resultant power can be defined as the sum of powers of all the lenses placed in contact together.
P =P₁ + P₂ + P₃ +....
It is given that power of the concave lens is, P₁ = -2 D
Power of the convex lens is, P₂ = +1.5 D
Thus, the resultant power when these two lenses are placed in contact with each other are: P = P₁ + P₂ = -2 D + 1.5 D = -0.5 D.