Question

An object 4cm tall is placed near the axis of a thin converging lens. If the focal length of the lens is 25 cm, where will the image be formed and what will be the size of the Image? Sketch the principal ray diagram.​

Answer 1

Answer:

From the lens formula,

=

v

1

−

u

1

=

f

1

⟹

f

1

=

24

1

−

−12

1

=

8

1

⟹f=8

When u=−12, the object is placed between F and 2F and the image is formed beyond 2F on the other side. This is a enlarged inverted image. If the object is moved away from the lens, the image moves towards the lens. So the screen should be moved towards the lens.

Magnification=

u

v

=

−12

24

=−2

When denominator increases, v decreases and hence magnification decreases