Question

list the sign convention that are followed in case of refraction of light through spherical lenses. Draw a diagram and apply these convention in determining the nature and focal length of a spherical lens which forms three times magnified real image of an object placed 16 cm from the lens​

Answer 1

Answer:

The sign conventions followed in case of refraction of light through spherical lenses is that distances to the left side of the lens are negative and distances to the right side of the lens are positive.

Focal length of the lens is 16cm and it is convex in nature.

Given object distance, u = 20cm

Image formed is real. Hence the lens is convex in nature

Magnification = 4 = -v/u

u = - 20cm

Therefore, v = 80cm

By lens formula, 1/f = 1/v - 1/u ==>

1/f = 1/80 - 1/-20  = -20 - 80 /-1600 ==>

f =  1600/100 = 16cm