Optical Instruments

An astronomical telescope uses two lenses of powers 10 D and 1 D.Its magnifying power in normal adjustment would be:

The expression for magnifying power of compound microscope is

The expression for astronomical telescope magnifying power is

The focal lengths of the objective and the eye piece of a compound microscope are $2.0 \mathrm{cm}$ and $3.0 \mathrm{cm},$ respectively. The distance between the objective and the eye piece is $15.0 \mathrm{cm}.$ The final image formed by the eye piece is at infinity. The two lenses are thin. The distance in $\mathrm{cm}$ of the object and the image produced by the objective, measured from the objective lens, are respectively

When an object is placed at a distance of $60cm$ From a convex mirror, the linear magnification produced is $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$. Where should the object be placed to obtain a magnification of $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right.$ ?

What are the eyepieces of the microscope called _____?

Is a microscope eyepiece always 10x?

Is Cassegrain telescope or astronomical telescope are same.

A Cassegrain telescope uses two mirrors as shown in the figure. Such a telescope is built with the mirrors $20 \mathrm{mm}$ apart. If the radius of curvature of the large mirror is $220 \mathrm{mm}$ and the small mirror is $140 \mathrm{mm},$ where will the final image of an object at infinity in $\mathrm{mm}$ be?

What is a cassegrain telescope?

Total magnification of compound microscope is $20$ while magnification for eye piece is $5$. If final image is formed at near point which is taken $20 \mathrm{cm}$ then focal length of eye piece is

The focal length of magnifying glass is $25 \mathrm{cm}$ then magnifying power this instrument when image is formed at infinity is ( near point for normal eye$=\mathrm{D}=25 \mathrm{cm}$)

An object is at distance $30 \mathrm{cm}$ from compound microscope of focal length $5 \mathrm{cm}$ and $25 \mathrm{cm}$ for objective and eye piece respectively. Magnifying power of microscope when image is formed at near point is 

Why eyepiece of a telescope is of short focal length while objective is of large focal length ?

A small laboratory telescope has an objective lens of focal, length $140 cm$ and an eye-piece of focal length $6 cm$. Then, separation between the objective and eye-piece is _____.

The focal length of an objective of a telescope is 3 meter and diameter 15 cm. Assuming for a normal eye, the diameter of the pupil is 3 mm for its complete use, the focal length of eye piece must be

 A telescope that uses two converging lenses is called refracting telescope.

 A telescope that uses two converging lenses is called _____ telescope.