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 = -[tex]\frac{v}{u}[/tex]
where
u = object distance
v = image distance
Now,
1.90 = [tex]\frac{v}{u}[/tex]
v = - 1.90u
To calculate the object distance, u by lens maker formula given by:
[tex]\frac{1}{F} = \frac{1}{u}+ \frac{1}{v}[/tex]
[tex]\frac{1}{16.5} = \frac{1}{u}+ \frac{1}{- 1.90u}[/tex]
[tex]\frac{1}{16.5} = \frac{1.90 - 1}{1.90u}[/tex]
[tex]\frac{1}{16.5} = \frac{ 0.90}{1.90u}[/tex]
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.
