Question

the image of an object placed at 24 cm in front of a lens is obtained on a screen at a distance of 72 cm from its calculate the focal length of the lens what would be the height of the image if the object is 2 centimetre in high also find the power of lens

Answer 1

Answer:

u = - 24 cm  

f = 8 cm ...(focal length of convex lens)  

 

1 over f equals space 1 over v minus 1 over u

1 over v space equals space 1 over f plus 1 over u

1 over v equals 1 over 8 plus fraction numerator 1 over denominator negative 24 end fraction equals 1 over 12

v space equals space 12 space c m space

T h u s space i m a g e space i s space f o r m e d space a t space a space d i s tan c e space o f space 12 space c m space b e h i n d space t h e space l e n s.

 

 

The image is formed to the right so, the image formed will real and inverted.

 

Magnification of image is given by,

 

m = v/u = 12/-24 = - 0.5  

 

This implies that magnification is -0.5 which means image is diminished.

Explanation: