Human Eye

The human eye can focus on objects at different distances by adjusting the focal length of the eye lens. This is due to

• presbyopia

• accommodation

• near-sightedness

• far-sightedness

The near point of a hypermetropic eye is 75 cm. What is the power of the lens required to correct this defect?

• • -2.66 D

• +2.66 D

• -1.26 D

• +1.26 D

The far point of a myopic eye is 80 cm in front of the eye. What is the power of the lens required to correct this defect?

• +1.25 D

• • -2 D

• +2 D

• • -1.25 D

The light sensitive cells get activated upon illumination and generate electric signals. These signals are sent to the brain via

• blind spot

• ciliary muscles

• retina

• optic nerve

Name the defect and its causes.

• Myopia i) focal length is too long ii) eye ball becomes small

• Hypermetropia i) excessive curvature of the eye lens ii) elongation of the eye ball

• Myopia i) excessive curvature of the eye lens ii) elongation of the eye ball

• Hypermetropia i) focal length is too long ii) eye ball becomes small

Name the defect of the eye and the lens used to correct his vision.

• Myopia, Convex lens

• Hypermetropia, Concave lens

• Myopia, Concave Lens

• Hypermetropia, Convex Lens

A child is able to see the blackboard clearly when he sits on the front bench. But he is not able to see the board clearly while sitting on the last bench. What defect of the eye is he suffering from?

• Hypermetropia

• Myopia

• Cataract

• Presbyopia

The crystalline lens of people at old age becomes milky and cloudy; this condition is known as ————-.

• Hypermetropia

• Myopia

• Cataract

• Presbyopia

When light rays enter the eye, most of the refraction occurs at the

• Crystalline lens

• The outer surface of the cornea

• iris

• pupil

A person gets out in the sunlight from a dark room. How does his pupil regulate and control the light entering the eye?

• The size of the pupil will decrease, and less light will enter the eye

• The size of the pupil will decrease, and more light will enter the eye

• The size of the pupil will remain the same, but more light will enter the eye

• The size of the pupil will remain the same, but less light will enter the eye