Answer: The eye defect called Hypermetropia
Which lens is used to correct this eye defect?
Such a person may see clearly upto a distance of a few metres. (ii) elongation of the eyeball. This defect can be corrected by using a
concave lens
of suitable power. Hypermetropia is also known as far – sightedness.
What is the power of lens formula?
The power of a lens is defined as the reciprocal of its focal length in meters, or
D = 1/f
, where D is the power in diopters and f is the focal length in meters. Lens surface power can be found with the index of refraction and radius of curvature.
How do you calculate power of corrective lens?
Let x be the distance of the actual far point from the eye (distance from the concave lens placed near the eye). Image formed,
v = – x, Focal length, f =?
Since the power is negative, this implies that the correcting lens is a concave lens.
What is the formula for hypermetropia?
P = +1.5 D
. So, the correct answer is “Option A”. Note: The convex lens used for correcting hypermetropia (or long-sightedness) should be of such a focal length (or power) that it forms a virtual image of the object (placed at a normal near point of 25 cm), at the near point of the hypermetropic eye.
What are the two main defects of vision?
As we saw earlier, the two major defects of eyes are
nearsightedness and farsightedness
. Myopia is the name of the condition for when a person is suffering from nearsightedness. This type of eye defect arises in a person because the power of the eye becomes too large.
How can defect be corrected?
Myopia can be corrected by
wearing glasses/contacts with concave lenses
these help to focus the image on the retina. Hyperopia: (farsightedness) This is a defect of vision in which there is difficulty with near vision but far objects can be seen easily.
Which lens has negative power?
concave lens
has negative power.
What is power of lens diagram?
Simply put, the power of a lens in Ray Optics is
its ability to bend light
. The greater the power of a lens, the greater is its ability to refract light that passes through it. For a convex lens, the converging ability is defined by power and in a concave lens, the diverging ability.
What is power of lens explain?
If a lens has a shorter focal length it is said to be more powerful. The power of a lens is defined as
the reciprocal of the focal length
. Lens power is measured in dioptres (D). Diverging (concave ) lenses have negative focal lengths, so they also have negative power values. …
What is effective power of a lens?
The Effective Power of a lens is
the refractive behavior of the lens when moved to a different distance
.
What is the unit of power of a lens?
A dioptre (British spelling) or diopter (American spelling)
is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres. (1 dioptre = 1 m
− 1
.)
What is the highest eye power?
20/10 vision
is thought to be the maximum visual acuity of human eyes without binoculars or other magnifying devices. Recent advances in optics have led to the creation of corrective lenses that can provide this ultra-sharp vision.
What is the near point formula?
When an object is 25.0 cm from the person’s eyes, the eyeglass lens must produce an image 1.00 m away (the near point), so that the person can see it clearly. … Therefore,
d
i
=−98.5cm
, where the minus sign indicates that the image is on the same side of the lens as the object.
What is hypermetropia with diagram?
The focal length of the eye lens has increased. Complete step by step answer: Hypermetropia (long-sightedness) is
a defect of an eye where a person cannot see nearby objects clearly
. The near point of Hypermetropia eye is more than D=25cm away.
Which lens is required for Hypermetropic man?
Longsightedness is corrected using
a convex (outward facing) lens
. This is placed in front of a hypermetropic eye, moving the image forward and focusing it correctly on the retina.
