Question

A lens has a power of -2.5 D. What is the focal length and nature of the lens?​

Answer 1

Answer:

Explanation:

We know that power of lens is P=  

f

1

​  

 

P=-25D

So −25=  

f

1

​  

 

f=−.04m=−4cm

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

Answer 2

Explanation:

P=1/f

this is the formula to find power of the lens

where p is power of lens and f is focal length of lens

therefore, -2.5=1/f

f=1/2.5

f=0.04

as it is positive it will produce real image