Question

.(a)Define 1 dioptre of power. Find the focallength of a lens of power–2.0D.

(b)Why does a lemon kept in water in a glass tumbler appear to be bigger than actual size?

Answer 1

Hope it helps...........

Answer 2

the power of a lens means the degree of to converge or diverge the light
power us equal one by focal length in m
p=1/f
-2 = 1/f
f = - 1/2 = .5


because of refraction