List of top Physics Questions on Optical Instruments

A telescope has an objective lens of focal length 144 cm and an eyepiece of focal length 6·0 cm. The magnifying power and the length of telescope tube will be respectively :
Write two advantages of reflecting telescope over refracting telescope.
In a telescope the objective has much larger aperture than the eyepiece. Why?
Draw a labelled ray diagram of a refracting telescope when it forms image of a distant object at infinity. Derive the expression for its magnifying power.
Give two reasons to explain why a reflecting telescope is preferred over a refracting telescope.
Draw the ray diagram to show the image formation by a refracting telescope and write the expression for angular magnification for the telescope in normal adjustment.
In a telescope the objective has much larger aperture than the eyepiece. Why?
Write two advantages of reflecting telescope over refracting telescope.
Draw a labelled ray diagram of a refracting telescope when it forms image of a distant object at infinity. Derive the expression for its magnifying power.
Give two reasons to explain why a reflecting telescope is preferred over a refracting telescope.
Draw the ray diagram to show the image formation by a refracting telescope and write the expression for angular magnification for the telescope in normal adjustment.
Two convex lenses of different focal lengths are in contact with each other. If the focal length of each lens is doubled, the focal power of the combination
Keeping the length of an astronomical telescope constant in normal adjustment, to increase its magnification from 4 to 9, the focal length of the eyepiece is to be decreased by 10 cm. The length of the telescope is
An astronomical telescope in normal adjustment has magnifying power \(5\) for distant objects. The separation between the objective and the eyepiece is \(36\) cm. The focal lengths of the objective and the eyepiece are respectively
In an astronomical telescope of $135\text{ cm}$ length kept in normal adjustment, if the difference between the focal lengths of the objective and eyepiece is $125\text{ cm}$, then the magnification of the telescope is:
The distance between the objective and eyepiece of an astronomical telescope in normal adjustment is $27\text{ cm}$ and its magnifying power is $8$. What is the focal length of the eyepiece?
The unit of power of a lens is
In a microscope of tube length $10\,\text{cm}$ two convex lenses are arranged with focal lengths $2\,\text{cm}$ and $5\,\text{cm}$. Total magnification obtained with this system for normal adjustment is $(5)^k$. The value of $k$ is ___.
The magnifying power of a simple microscope can be increased by using
There is a compound microscope of lenses having focal lengths 2 cm and 5 cm and tube length 10 cm. Find magnifying power in normal adjustment. If your answer is $5^\alpha$, find '$\alpha$' :
A microscope has an objective of focal length \(f_o = 2\) cm and an eyepiece of focal length \(f_e = 4\) cm. The tube length of the microscope is \(L = 40\) cm. If the distance of distinct vision of eye is \(D = 25\) cm, the magnification in the microscope is:
Resolving power of a telescope can be increased by increasing
The length of the compound microscope is $15\text{ cm}$ . The magnifying power for relaxed eye is 25 . If the focal length of eye lens is $6\text{ cm}$ then the object distance for objective lens will be}
Resolving power of a telescope can be increased by increasing
The simple microscope having a lens of focal length 5 cm gives the magnification of (least distance of distinct vision \(= 25\) cm)