Question

A lens has -4 D power. What is the nature of the lens?​

Answer 1

⇒The power of this lens has minus sign, so it is a concave lens

Answer 2

Answer:

If the lens has negative power then it is a concave lens..

$\red{Additional information}$

P = -4D

P = 1/f

f = 1/P

f = 1/-4

f = -2.5 cm

$\green{THANK YOU}$