Question

The focal lengths of the objective and eye-piece of
a compound microscope are 2 cm and 3 cm
respectively. The distance between the objective
and eye-piece is 15 cm. The final image formed is
at infinity. The distances in cm of object and image
form objetive are

​

Answer 1

Explanation:

According to the question final image is formed at infinity.

⇒ The object for eyepiece (image formed by objective lens)should be at a distance of f=3cm from it.

Applying lens image formation on objective lens,

2

1

=

12

1

−

x

1

x

1

=

12

1

−

2

1

=

12

−5

x=−2.4cm, -ve indicates distance is towards left side of lens.

2.4and12cm is correct.