EASY
JEE Main
IMPORTANT
Earn 100

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?

Important Questions on Optical Instruments

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?
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 18
A professor reads a greeting card received on his 50th birthday with +2.5 D glasses keeping the card 25 cm away. Ten years later, he reads his farewell letter with the same glasses but he has to keep the letter 50 cm away. What power of lens should he now use?
MEDIUM
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 19
A normal eye has the retina 2 cm behind the eye-lens. What is the power of the eye-lens when the eye is (a) fully relaxed, (b) most strained?
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 20
The near point and the far point of a child's eye are at 10 cm and 100 cm, respectively. If the retina is 2.0 cm behind the eye-lens, what is the range of the power of the eye-lens?
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 21
A nearsighted person cannot see beyond 25 cm. Assuming that the separation of the glass from the eye is 1 cm, find the power of the lens needed to see distant objects clearly.
EASY
JEE Main
IMPORTANT
CONCEPTS OF PHYSICS [VOLUME 1]>Chapter 19 - Optical Instruments>EXERCISES>Q 22
A person has a near point at 100 cm. What power of lens is needed to read at 20 cm if he/she uses (a) contact lens, (b) spectacles having glasses 2.0 cm separated from the eyes?