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प्रश्न
Give scientific reason:
One can sense colours only in bright light.
उत्तर
- The light sensitive screen of the eye, called the retina, has two types of light sensitive cells.
- Rod cells are concerned with vision in dim light and cone cells are responsible for the vision in presence of light.
- Cone cells are also concerned with colour perception. They do not respond to dim light or no light.
- Thus, the knowledge of the colour is possible in presence of light and not in dark.
- Hence, we can identify and differentiate colours in presence of light.
संबंधित प्रश्न
Write the function of the following part of the human eye: Cornea
Night birds have ______ cones than rods in their eyes.
A person got his eyes tested by an optician. The prescription for the spectacle lenses to be made reads :
Left eye : +2.50 D
Right eye : +2.00 D
Which lens bends the light rays more strongly?
What is the name of:
the light-sensitive layer in the eye?
Fill in the following blank with suitable words:
When light is dim, the pupil becomes................
Fill in the following blank with suitable word:
To bring light from a near object to a focus on the retina of the eye, the convex eye-lens need to be made....................
What changes take place in the shape of eye-lens:
when the eye is focused on a near object?
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?
Explain why, we cannot see our seats first when we enter a darkened cinema hall from bright light but gradually they become visible.
The term " accommodation" as applied to the eye, refers to its ability to:
(a) control the light intensity falling on the retina
(b) erect the inverted image formed on the retina
(c) vary the focal length of the lens
(d) vary the distance between the lens and retina
The human eye possesses the power of accommodation. This is the power to:
(a) alter the diameter of the pupil as the intensity of light changes
(b) distinguish between lights of different colours
(c) focus on objects at different distances
(d) decide which of the two objects is closer.
Nocturnal animals (animals which sleep during the day and come out at night) tend to have wide pupils and lot of rods in their retinas. Suggest reasons for this.
fill in the following blank with suitable word:
A person is short-sighted if his eyeball is too............Spectacles with a .............lens are needed. A person is long-sighted if his eyeball is too............Spectacles with a ................lens are needed. These focus light rays exactly on to the..........
After testing the eyes of a child, the optician has prescribed the following lenses for his spectacles:
Left eye : + 2.00 D
Right eye : + 2.25 D
The child is suffering from the defect of vision called:
(a) short-sightedness
(b) long-sightedness
(c) cataract
(d) presbyopia
A person got his eyes tested. The optician's prescription for the spectacles reads:
Left eye: − 3.00 D
Right eye: − 3.50 D
The person is having a defect of vision called:
(a) presbyopia
(b) myopia
(c) astigmatism
(d) hypermetropia
Fill in the following blank with suitable word:
Having two eyes enables us to judge.................more accurately.
Explain clearly why, a person who has lost the sight of one eye is at a disadvantage compared with the normal person who has two good eyes.
Name two animals having eyes:
at the front of the head.
With both eyes open, a person's field of view is about:
(a) 90°
(b) 150°
(c) 180°
(d) 360°
Having two eyes gives a person:
(a) deeper field of view
(b) coloured field of view
(c) rear field of view
(d) wider field of view
Differentiate between members of the following pair with reference to what is asked in bracket.
Rod and cone cells (pigment contained)
Sometimes you remember a vivid picture of a dream you saw. What is the role of your eyes in this experience?
Name the muscles of the eye responsible for the power of accommodation.
Define the following:
Yellow spot
Write whether the following is true or false:
Rods are the receptor cells in the retina of the eye sensitive to dimlight.
Choose the correct answer.
In the chemistry of vision, the photosensitive substance is _________________
Choose the correct answer :
The rods and cones of a vertebrate retina function is to _________
State the Function:
Vitreous humour
Write the name.
The fleshy screen behind cornea.
Vision defect that increases distance between the lens of the eye and retina of the eye is termed as myopia.
Write an Explanation.
Farthest distance of distinct vision
______ is tough and thick white sheath that protects the inner parts of the eye.
The larynx has fold of tissue which vibrate with the passage of air to produce sound.
The black opening between the aqueous humour and the lens is called ____________.
Name the part of the eye which gives colour to the eyes.
Eyes of the nocturnal birds have large cornea and a large pupil. How does this structure help them?
Describe the parts in the external structure of the eye.
Explain the role of the part of human eye responsible for power of accommodation of human eye.
The layer in the eye where sensory cells (rods and cones) are located ______.
