EASY
JEE Main
IMPORTANT
Earn 100

A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5 cm and the tube length is 6.5 cm. Find the focal length of the eyepiece.

Important Questions on Optical Instruments

EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 10
A compound microscope consists of an objective of focal length 1 cm and an eyepiece of focal length 5 cm. An object is placed at a distance of 0.5 cm from the objective. What should be the separation between the lenses so that the microscope projects an inverted real image of the object on a screen 30 cm behind the eyepiece?
HARD
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 11

An optical instrument used for angular magnification has a 25 D objective and 20 D eyepiece. The tube length is 25 cm when the eye is least strained.

(a) Whether it is a microscope or a telescope?

(b) What is the angular magnification produced?

EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 12
An astronomical telescope is to be designed to have a magnifying power of 50 in normal adjustment. If the length of the tube is 102 cm, find the powers of the objective and the eyepiece.
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 13
The eyepiece of an astronomical telescope has a focal length of 10 cm. The telescope is focussed for normal vision of distant objects when the tube length is 1.0 m. Find the focal length of the objective and the magnifying power of the telescope.
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 14
A Galilean telescope is 27 cm long when focussed to form an image at infinity. If the objective has a focal length of 30 cm, what is the focal length of the eyepiece?
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 15
A farsighted person cannot see objects placed closer to 50 cm. Find the power of the lens needed to see the objects at 20 cm.
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 16
A nearsighted person cannot clearly see beyond 200 cm. Find the power of the lens needed to see objects at large distances.
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 17
A person wears glasses of power -2.5 D. Is the person farsighted or nearsighted? What is the far point of person without the glasses?