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A question (stem not visible in provided images) regarding optical instruments/components:
a concave lens of suitable power
a plane glass plate
a convex lens of suitable power
a plane mirror
a convex lens of suitable power
The condition described is 'Hypermetropia' (farsightedness), where a person can see distant objects clearly, but nearby objects appear blurred because the image is focused behind the retina. This defect is corrected by using a convex lens of appropriate power, which converges the incoming light rays before they enter the eye, allowing them to focus exactly on the retina.
The condition described is 'Hypermetropia' (farsightedness), where a person can see distant objects clearly, but nearby objects appear blurred because the image is focused behind the retina. This defect is corrected by using a convex lens of appropriate power, which converges the incoming light rays before they enter the eye, allowing them to focus exactly on the retina.
Think of it like a camera lens that cannot 'zoom in' or focus close enough; the convex lens acts like an additional magnifying glass that helps 'push' the focus point back onto the film (retina).
Remember 'H-C-C': Hypermetropia is corrected by Convex lens.
P=f1тАЛ тАФ Power of lens where f is focal length in meters
f1тАЛ=v1тАЛтИТu1тАЛ тАФ Lens formula for corrective power calculation
In a healthy eye, light rays from a near object are focused on the retina. In a hypermetropic eye, the eyeball is too short or the eye lens has insufficient converging power, causing the image to form behind the retina. A convex lens, which is a converging lens, provides the extra convergence required to shift the image point forward onto the retina.
Hypermetropia is also known as farsightedness.
The near point of a hypermetropic eye is further away than the normal 25┬аcm.
Convex lenses have positive power, which is measured in Dioptres (D).
Efficiently restores clear near vision
Non-invasive and easily replaceable
Requires constant use for reading
Can cause magnification of eye size in high-power lenses
Presbyopia correction
Hypermetropia treatment
Normal near point is 25┬аcm.
Option A is incorrect because a concave lens is used for Myopia (nearsightedness) to diverge light rays.
Option B is incorrect because a plane glass plate would cause no refraction or convergence.
Option D is incorrect because a plane mirror reflects light and does not converge it to focus on a retina.
C is correct тАФ A convex lens of suitable power is used to correct hypermetropia by increasing the converging power of the eye.
Always remember: 'Myopia' (short) uses 'Concave' (long word), while 'Hypermetropia' (long) uses 'Convex' (short word). This simple trick helps avoid confusion in exams!
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