Question

A convex lens has a focal length of 25 cm. Calculate the distance of the object from the lens if the Image is to be formed on the opposite side of the lens at a distance of 75 cm from the lens is

Answer 1

Answer:

u = - 37.5

Step-by-step explanation:

Given,

Convex lens

focal length ( f ) = + 25 cm

image ( v ) = + 75 cm

To find : u = ?

By lens formula,

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

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

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

      = ( 1 / 75 ) - ( 1 / 25 )

      = ( 1 / 75 ) - ( 3 / 75 )

      =  ( 1 - 3 ) / 75

1 / u = - 2 / 75

u = 75 / - 2

  = - 75 / 2

u = - 37.5 cm

Therefore, the distance of the object from the lens if the Image is to be formed on the opposite side of the lens at a distance of 75 cm from the lens is - 37.5 cm