A far sighted man, who has lost his spectacles, reads a book by looking through a small whole (3-4 mm) in a sheet of paper. The reason is ____.
because the hole produces an image of the letters at a longer distance
because in doing so, the focal length of the eye lens is effectively increased
because in doing so, the focal length of the eye lens is effectively decreased
None of the above
For a normal eye, the least distance of distinct vision is ____.
0.25 m
0.50 m
25 m
Infinite
For the myopic eye, the defect is cured by ____.
convex lens
concave lens
cylindrical lens
toric lens
Lens used to remove long sightedness (Hypermetropia) is ____.
or
A person suffering from Hypermetropia requires which type of spectacle lenses ____.
concave lens
plano-concave lens
convexo-concave lens
convex lens
Substance on the choroids is ____.
Japan black
Nigrim pigment
carbon black
platinum black
Astigmatism (for a human eye) can be removed by using ____.
concave lens
convex lens
cylindrical lens
prismatic lens
Circular part in the centre of retina is called ____.
blind spot
yellow spot
red spot
None of the above
Image formed on the retina is ____.
real and inverted
virtual and erect
real and erect
virtual and inverted
If there had been one eye of the man, then ____.
image of the object would have been inverted
visible region would have decreased
image would have not been seen three dimensional
Both B and C
A person cannot see distinctly at the distance less than one meter. Calculate the power of the lens that he should use to read a book at a distance of
25 cm ____.
+ 3.0 D
+ 0.125 D
– 3.0 D
+ 4.0 D
How should people wearing spectacles work with a microscope?
They cannot use the microscope at all
They should keep on wearing their spectacles
They should take off spectacles
Both B and C
A man who cannot see clearly beyond 5 m wants to see stars clearly. He should use a lens of focal length ____.
– 100 m
+ 5 m
– 5 m
Very large
A man can see only between 75 cm and 200 cm. The power of lens to correct the near point is ____.
+ 3 D
– 3 D
Image is formed for the short sighted person at ____.
retina
before retina
behind the retina
image is not formed at all
A man can see the objects up to a distance of one meter from his eyes. For correcting his eye sight so that he can see an object at infinity, he requires a lens whose power is :
or
A man can see up to 100 cm of the distant object. The power of the lens required to see far objects is ____.
+ 0.5 D
+ 1.0 D
+ 2.0 D
– 1.0 D