The least distance of distinct vision for a young adult with normal vision is about: (a) 25m (b) 2.5cm (c) 25cm (d) 2.5m
(c) 25cm
(a) Explain the functions of the following parts of the eye: (a) cornea (b) iris (c) pupil (d) ciliary muscles (e) eye-lens (f) retina (g) optic nerve (b) If you walk from a dark room into sunlight and back again into dark room, how would your pupils alter in size? What makes this happen? (c) Explain why we cannot see our seats first when we enter a darkened cinema hall from bright light but gradually they become visible.
(a)The cornea is the portion of the eye’s front that allows light to enter.(b) Iris: The iris regulates how much light enters the eye.(c) Pupil: The pupil controls how much light enters the eye.(d) Ciliary muscles: These help the eye lens to contract and relax.(e) The eye lens aids in concentrating light on the retina.(f) …
(a) What happens to the size of pupil of our eye (i) in dim light (ii) in bright light (b) Name the cells on the retina of an eye which are sensitive to (i) bright light (ii) dim light (iii) sensation of colour.
(a) (i) In dim light, pupil becomes large (ii) In bright light, pupil becomes small (b) ( i) Cones (ii) Rods (iii) Cones
(a) How does the convex eye lens differ from the ordinary convex lens made of glass? (b) List in order the parts of the eye through which light passes to reach the retina.
(a) The convex eye lens differs from a regular convex lens in that the ciliary images govern its focal length, whereas a regular convex lens’s focal length is maintained by adjusting the glass’s focal length.(b) Retina, cornea, pupil, and eye lens.
What are rods and cones in the retina of an eye? Why is our night vision relatively poor compared t the night vision of an owl ?
The retina of the eye is made up of rod and cone cells. Rods are cells with a rod-like structure that are sensitive to low light. Cones are formed like cones and are sensitive to intense light. Due to the presence of fewer rod cells than owls, humans have less effective night vision than owls.
There are two types of light-sensitive cells in the human eye: (a) Where are they found? (b) What is each type called? (c) To what is each type of cell sensitive?
(a) The retina contains both of the types of light-sensitive cells.(b) Rods and cones are the names of these cells.(c) While cones are sensitive to bright light, rods are sensitive to low light.
Describe and explain how a normal eye can see objects lying at various distances clearly.
The ciliary muscles are used to help the eye concentrate on distant things. The suspensory ligaments are pulled and connected to the eye lens as the ciliary muscles completely relax.
Ciliary muscles of human eye can contract or relax. How does it help in the normal functioning of the eye?
The eye lens becomes thin and is easier to perceive distant things when the ciliary muscle is relaxed. The eye lens thickens when the ciliary muscle contracts, making it simple to view items in nearby areas. The ciliary muscle assists the eye’s normal functioning in this way.