Home
Class 12
PHYSICS
A young boy can adjust the power of his ...

A young boy can adjust the power of his eye lens between 50 D and 60 D. His far point is infinity. A. What is the distance of his retina from the eye-lens? b. What is the near point?

Text Solution

Verified by Experts

a. When the eye is fuly relaxed, its focal length is largest and the power of the eye lens is minimum. This power is 50 D according to the given data. The focal lengts is `1/50m=2cm.` As the far point is at infinity, the parallel rays coming from infinity are focussed on the retiN/A in the fuly relaxed condition. HEnce, the distance of the retinN/A from the lens equals the focal length which is 2 cm.
b. when the eye is focussed at the near point, the power is maximum which is 60 D. the focal lenth in this case is `f=1/60m=5/3cm. The image is formed on the retiN/A and thus v=2 cm. We have,
`1/v-1/u=1/f`
or `1/u=1/v-1/f=1/(2cm)-3/(5cm)`
or `u=-10cm`
The near point is at 10 cm
Promotional Banner

Topper's Solved these Questions

  • OPTICAL INSTRUMENTS

    HC VERMA|Exercise Question for short Answer|12 Videos

  • OPTICAL INSTRUMENTS

    HC VERMA|Exercise Objective -1|11 Videos

  • OPTICAL INSTRUMENTS

    HC VERMA|Exercise Exercises|23 Videos

  • MAGNETIC PROPERTIES OF MATTER

    HC VERMA|Exercise Exercise|9 Videos

  • PERMANENT MAGNETS

    HC VERMA|Exercise Exercise|25 Videos

Similar Questions

Explore conceptually related problems

What is near point and far point of a human eye ?

The near point and the far point of a child are at 10 cm and 100 cm. If the retina is 2.0 cm behind the eye-lens, what is the range of the power of the eye-lens?

A person can see clearly objects only when they lie between 50 cm and 400 cm from his eyes.In order to increase the maximum distance of distinct vision to infinity,the type and power of the correcting lens,the person has to use , will be

At what distance should a watchmaker hold his lens from the watch?

An amateur astronomer wishes to estimate roughly the size of the Sun using his crude telescope consisting of an objective lens of focal length 200 cm and an eyepiece of focal length 10 cm. By adjusting the distance of the eyepiece from the objective, he obtains an image of the Sun on a screen 40 cm behind the eyepiece. the diameter of the sun's image is measured to be 6.0 cm. What is his estimate of the Sun's size given that the average Earth-sun distance is 1.5 xx 10^(11) m ?

For a normal eye, provides a converging power of 40Dand the least converging power of the eye lens behind the cornea is 20D.usingh this information, the retina and the corner eyes lens can be estimated to be

A point object at a distance of 36 cm from a convex lens of focal length 10 cm, is moved by 10 cm in 2 sec along principal axis towards the lens. Then image will aslo change its position. a. Write the law which relates object and image distance from the lens. b. Find the inwal and final position of the image and calculate average speed of image . c. A man argues that the image will move uniformly at the same speed as that of object What is your opinion ? Justify.

If the focal lengths of the objective and eyepiece of a microscope are 2 cm and 5 cm respectively and the distance between them is 20 cm, what is the distance of the object from the objective when the image seen by the eye is 25 cm from eyepiece? Also find the magnifying power.