In a compound microscope, the focal lengths of two lenses are 1.5 cm and 6.25 cm. An object is placed at 2 cm from the objective and the final image is formed at 25 cm from the eye lens. The distance between the two lenses is … (in cm).

Options

A. 6
B. 7.75
C. 9.25
D. 11

Answer

D

Explanation

For, objective,
`u=-2cm,f=1.5m`
By `1/v-1/u=1/f`, we have,
`1/v=1/1.5-1/2v=6cm`
For eyepiece, v = -25cm, f = 6.25cm
Using `1/v-1/u=1/(f.)` we get
`1/u=1/(-25)-1/6.25`
u = - 5 cm

So, distance between two lenses = 11 cm.