Question

plz answer I want step by step plz​

Answer 1

Given:

Object distance, u = -12cm

Power, P = -5D

Focal length, f = ?

Image distance, v = ?

To calculate focal length:

P = 100/f (in cm)

-5 = 100/f

f = 100/-5

f = -20cm

So, Focal length, f = -20cm

To calculate image distance:

Using lens formula,

(1/v) - (1/u) = (1/f)

(1/v) = (1/f) + (1/u)

(1/v) = (1/-20) + (1/-12)

(1/v) = (-3/60) + (-5/60)

(1/v) = -8/60

v = -60/8 = -7.5cm

So, Image distance, v= -7.5cm