Advertisements
Advertisements
प्रश्न
Solve the following question:
The near point of the eye of a person is 50 cm. Find the nature and power of the corrective lens required by the person to enable him to see clearly the objects placed at 25 cm from the eye?
Advertisements
उत्तर
Since the near point of the eye is 50 cm which is greater than 25 cm, a person is suffering from hypermetropia.
Object distance (u) = - 25cm
Image distance (v) = - 50cm
Using lens formula
`1/"f" = 1/"v" - 1/"u"`
`1/"f" = 1/(-50) - 1/(-25)`
`1/"f" = -1/50 + 1/25`
`1/"f" = (-1+2)/50`
`1/"f" = 1/50`
`"f"` = +50 cm
Since the focal length of the lens is positive, corrective lens required is convex lens.
`"f"` = +50cm
`"f"` = +0.5m
Power (P) of corrective lens will be
`"P" = 1/("f"("m"))`
`"P" = 1/0.5`
`"P" = + 2 "D"`
APPEARS IN
संबंधित प्रश्न
Millions of people in the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organised a campaign in your neighbourhood in order to create awareness about this fact. If you are asked to participate in this mission, how would you contribute in this noble cause?
(i) State the objective of organising such campaigns.
(ii) List two arguments which you would give to motivate the people to donate their eyes after death.
(iii) List two values which are developed in the persons who actively participate and contribute in such programmes.
Explain two possible reasons of myopia. How can it be corrected? Explain with a suitable diagram.
What is the scientific name of
long-sightedness?
An eye has a far point of 2 m. What type of lens in spectacles would be needed to increase the far point to infinity? Also calculate the power of lens required. Is this eye long-sighted or short-sighted?
What is Hypermetropia (far sightedness)?
What type of lens is used to correct Hypermetropia?
Mention, if the following statement is True or False
Hypermetropia is a defect of the eye caused due to the eyeball elongation
Choose the Odd One Out:
Given below is a diagram showing a defect of vision. Name the defect of vision and draw an accurately labelled diagram to correct this defect.
