Question

An object is placed at a distance of 2.5cm from the objective lens of focal length 2cm. The focal length of eye piece is 5cm. Find magnifying power and length of microscope if image is at infinity.

Answer 1

Hey there...

using the formula, 1/v - 1/u = 1/f
=> 1/v - 1/(5/2) = 1/2
=> 1/v = 1/2 - 2/5
=> 1/v = 1/10
=> v = 10

Now, for calculating Magnifying power (M.P.) , using the formula,
v/u × D/fe = M.P.

=> M.P. = 10 / -(5/2) × 25 / 5

= 20/-5 × 25/5
= -4 × 5
= -20

Here, M.P. = -20cm

and length (L) = v + ue
L(max.) = 10 + fe
= 10+5
= 15cm


Hope it helps....