Image formed on retina in human eye is:
(a) erect but looks inverted
(b) inverted but looks erect
(c) erect and looks also erect
(d) inverted and looks also inverted
Eye lens is:
(c) convex and concave
(d) none of these
The part of the eyes refracts light entering the eye from external objects is
The light sensitive cell present on retina and is sensitive to the intensity of light is:
(c) both rods and cones
(d) none of these
The clear sky appears blue because
(а) blue light gets absorbed in the atmosphere.
(b) ultraviolet radiations are absorbed in the atmosphere.
(c) violet and blue lights get scattered more than lights of all other colours by the atmosphere.
(d) light of all other colours is scattered more than the violet and blue colour lights by the atmosphere.
One cannot see through the fog, because
(a) refractive index of the fog is very high
(b) light suffers total reflection at droplets
(c) fog absorbs light
(d) light is scattered by the droplets
Perception of colours by human eye is possible:
(a) at retina
(b) by rod shaped cells of retina
(c) cone shaped cells of retina
(d) by yellow spot.
The black opening between the aqueous humour and the lens is called
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
(a) is scattered the most by smoke or fog.
(b) is scattered the least by smoke or fog.
(c) is absorbed the most by smoke or fog.
(d) moves fastest in air.
The focal length of the eye lens increases when eye muscles
(a) are relaxed and lens becomes thinner
(b) contract and lens become thicker
(c) are relaxed and lens becomes thicker
(d) contract and lens become thinner
What is colour-blindness? What kind of retinal cells are lacking in person suffering from this defect?
Why there is no dispersion of light refracted through a rectangular glass slab?
What is astigmatism? What causes astigmatism? How is astigmatism corrected?
What is meant by ‘persistence of vision’? We are able to see the movie picture in a cinema hall. How does this happen?
Why does it take some time to see objects in a dim room when you enter the room from bright sunlight outside?
What is Tyndall effect? Explain with an example.
A person needs a lens of power -4.5 D for correction of her vision.
(a) What kind of defect in vision is she suffering from?
(b) What is the focal length of the corrective lens?
(c) What is the nature of the corrective lens?
A person cannot see objects nearer than 75 cm from his eyes while a person with normal vision can see objects upto 25 cm from his eyes. Find the nature, the focal length and the power of the correcting lens used for the defective vision.
A person can see clearly only up to 3 metres. Prescribe a lens for spectacles so that he can see clearly up to 12 metres.
Write about power of accommodation of human eye. Explain why the image distance in the eye does not change when we change the distance of an object from the eye?