Question

two lens of power +2.3D and -1.3D is combined. what is the focal length of combination of lens ?

Answer 1

P1 = 2.3D

P2 = -1.3D

Combined power = P1+P2

=>2.3D-1.3D

=>1D. {yeehaw for one direction all the way :> okay I'll shut :3}

We know,

Power = 1/focal length(in metres)

1 = 1/focal length

=>focal length = 1m = 100cm

Cheers!