The power of a convex lens of focal length 40 cm is ___________.

Correct option is C

Given:

Focal length ($$f$$) = 40cm

Formula used:

Power of lens (P) = $$\frac{100}{f}$$ 

Where (P)= Power of lens (in Diopters,D)

​$$f=$$ Focal length (In cm/m)

Solution:

Power of length (P) = $$\frac{100}{f}$$ = $$\frac{100}{40}=2.5D$$

for Convex lens Power is = +2.5D

Thus the correct answer is (C)