Question

A student needs spectacles of power-0.5 D for the correction of his vision.
(i) Name te defect in vision the student is suffering from.
(ii) Find the nature and focal length of the corrective lens.
(iii) List two causes of this defect

Answer 1

$hello \: mate$

1) Myopia

2) Nature: Concave lens(Diverging lens)

Focal length=

➡P=1/f

➡ -0.5=1/f

➡f=-1/0.5

➡f= -2 m

3)

➡Due to high converging power of the eye lens

➡Due to the eye ball being too long

Answer 2

the student is suffering from nearsightedness, which requires a concave lens of -2 meters focal length. The two causes of this defect are genetics and excessive screen time.

(i) The student needs spectacles of power 0.5 D, which means that he is suffering from nearsightedness or myopia. This is a defect in a vision where a person can clearly see objects that are close but has difficulty seeing objects at a distance.

(ii) The nature of the corrective lens required by the student is concave. The focal length of the lens can be calculated using the formula 1/f = 1/d + 1/d', where d is the distance of the object from the lens and d' is the distance of the image from the lens. For a concave lens, the focal length is negative, and in this case, the focal length is -2 meters.

(iii) Two causes of nearsightedness are genetics and excessive screen time. Genetics plays a role in the development of nearsightedness, and it is more common in people with a family history of the condition. Excessive screen time, especially for close-up activities like reading and working on a computer, can also lead to the development of nearsightedness as the eyes are overworked and strained.

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