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A convex lens has a focal length of 16.5 cm. Where on the lens axis should an object be placed in order to get a virtual, enlarged image with a magnification of 1.90?

User Ekcrisp
by
7.8k points

1 Answer

5 votes

Answer:

Object should be placed at a distance, u = 7.8 cm

Given:

focal length of convex lens, F = 16.5 cm

magnification, m = 1.90

Solution:

Magnification of lens, m = -
(v)/(u)

where

u = object distance

v = image distance

Now,

1.90 =
(v)/(u)

v = - 1.90u

To calculate the object distance, u by lens maker formula given by:


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


(1)/(16.5) = (1)/(u)+ (1)/(- 1.90u)


(1)/(16.5) = (1.90 - 1)/(1.90u)


(1)/(16.5) = ( 0.90)/(1.90u)

u = 7.8 cm

Object should be placed at a distance of 7.8 cm on the axis of the lens to get virtual and enlarged image.

User Jros
by
7.7k points
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