CBSE Class 10CBSE
Share
Notifications

View all notifications

A Person Suffering from the Eye-defect Myopia (Short-sightedness) Can See Clearly Only up to a Distance of 2 Metres. What is the Nature and Power of Lens Required to Rectify this Defect? - CBSE Class 10 - Science

Login
Create free account


      Forgot password?

Question

A person suffering from the eye-defect myopia (short-sightedness) can see clearly only up to a distance of 2 metres. What is the nature and power of lens required to rectify this defect?

Solution

A person suffering from myopia can correct the defect by wearing spectacles with concave lenses. In order to find the power of the concave lens required, we have to first calculate its focal length.
Given that the far point of the myopic person is 2 m from the eye (the person can see an object kept at infinity if the image of the object is formed at the far point of 2 m from the eye).
u = ∞ (distance of the object)
v = -2 m (far point in front of the lens)
f = ? (focal length)
The focal length can be calculated using the lens formula `1/v-1/u=1/f` 

Substituting the values in the formula, we get  `1/-2-1/oo=1/f` 

∴ f = -2 m
Now that we know the focal length of the concave lens, the power can be calculated.
Power  P=`1/f("inmeters")` 

p=`1/-2=-0.5` diptres 

Therefore, the power of the concave lens required to rectify the defect is -0.5 dioptres.

  Is there an error in this question or solution?

APPEARS IN

Video TutorialsVIEW ALL [1]

Solution A Person Suffering from the Eye-defect Myopia (Short-sightedness) Can See Clearly Only up to a Distance of 2 Metres. What is the Nature and Power of Lens Required to Rectify this Defect? Concept: Defects of Vision and Their Correction.
S
View in app×