When light rays enter the eye, most of the refraction occurs at the
When light enters the eye, most of the refraction takes place at the outer surface of the cornea. The crystalline lens only makes some finer adjustment.
The focal length of the eye lens increases when eye muscles
Cilliary muscles modify the curvature of eye lens. When eye muscles are relaxed, eye lens becomes thinner thereby are relaxed, eye lens becomes thinner thereby increase in the focal length of eye lens.
The amount of light entering the eye is controlled by
Iris controls the amount of light entering the eye.
The Iris automatically adjust the size of the pupil according to the intensity of light received by the eye.
If it is daytime, the iris contracts the pupil and reduces the amount of light entering.
If it is night, iris expands the pupil so that more light may enter the eye.
When tight rays enter the eye, most of the refraction occurs at the
Most of the refraction for light rays entering the eye occurs at the outer surface of cornea which acts a primary lens converging in nature.
When the light is very bright
When the light is very bright the iris makes the pupil contract so as to control the quantity of light entering the eye.
The bluish colour of water in deep sea is due to
The fine water molecules mainly scatter blue light due to its shorter wavelength.
Eye lens form the image of an object situated in front of it at the retina. The image formed is
The image of an object situated in front of eye is formed on the retina. The image formed is a real, inverted and diminished image
The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light
Red colour has longer wavelength so least scattered by smoke or fog.
The range of vision of a normal human eye is from
The normal range of vision for a human eye is from infinity to 25 cm.
The clear sky appears blue because
Violet and blue colour have shorter wavelength.
So, they scattered more than lights of other colour by the molecules present in the atmosphere.
The change in focal length of eye lens, so as to focus the image of objects situated at varying distance in front of eye, is done by the action of the
To focus the objects, situated at different distances from the eye, distinctly at the retina the eye lens adjusts its focal length. This adjustment of focal length of eye lens is achieved by the contraction/relaxation of the ciliaiy muscles.
Twinkling of stars is due to atmospheric
Twinkling of star is due to atmospheric refraction of starlight caused by the gradual change in refractive index of different air layers at different height, the apparent position of star keeps on changing.
A person cannot see distinctly objects kept beyond 80 cm. This defect of vision is known as
A person, who cannot see objects placed beyond 80 cm distinctly, is suffering from the myopia or short-sightedness defect of vision of eye.
At noon the sun appears white as
At noon, the sun is at top and the light rays coming from the sun have to travel lens distance hence, all colours get scattered very less even blue and violet.
A student sitting on last bench in a classroom cannot see clearly words written on the blackboard. He is suffering from
A student, who cannot read words written on blackboard from the last bench of his class room, is suffering from the myopia or short-sightedness defect of vision of eye.
A prism ABC (with BC as base) is placed in different orientations. A narrow beam of white light is incident on the prism as shown in figure. In which of the following cases, after dispersion, the third colour from the top corresponds to the colour of the sky?
In figure (a) base BC of the prism is at the bottom, then violet colour lies at the bottom but in figure (b), the base BC is at the top, then violet would be at the top after dispersion, and third colour would be blue.
A girl can see distant objects clearly but cannot see an object situated close to her eye. She is suffering with
A girl who can see distant objects clearly but is unable to see clearly the objects situated close to her eye, is suffering from hypermetropia or long-sightedness defect.
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power
Person cannot see distant objects clearly. So he is suffering from myopia. The defect is corrected by using concave lens of power
A student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his textbook. Which of the following statements is correct ?
A student sitting on the last bench of class can read the letters written on the blackboard. It means his farsight is normal. However, he cannot read the letters written in his textbook distinctly. It means he is suffering from long-sightedness (hypermetropia) and the near point of his eye has receded away
One cannot see through the fog, because
Objects are not visible through the fog because droplets scatter the light rays.