Flash Card
Distance between optical centre and centre of curvature is called as .............. ..
People suffering from both myopia and hypermetropia, needs ............. lens
The ............. cells respond to the colour and give information about the colour of the object to the brain.
For the normal human eye, minimum distance of distinct vision is ............. cm.
A type of lens which is thinner at centre than at edges is........ .
A convex lens of short focal length held very close to the eye, to observe minute objects clearly is called as
A ............... lens always produces virtual and diminished image.
Defective refraction by the lenses causes
Bifocal lens is required to correct ............... defect.
When we see an object, the image formed on the retina is
The capacity of a lens to converge or diverge incident rays is called .............. of the lens.
The final image produced by a simple microscope is
The colour of the eye is determined by
According to Cartesian sign conventions, all the distances are measured from the
Principal focus of a magnifying glass is
An object is placed at a distance of f/2 from a convex lens of focal length f. The image will be
A convex lens forms a virtual image of an object placed ............. .
At what distance a watch maker must hold his lens from the watch?
A focal length of a lens is 20 cm. What is power of a lens in dioptre?
The image obtained while finding the focal length of convex lens is
The focal length of a concave lens, according to Cartesian sign conventions is
A person suffering from hypermetropia
Which of the following is wrong? Here M represents magnification of a lens.
There is a small hole of changing diameter at the centre of the iris which is called
The power of spectacles for hypermetric person
A student obtained a clear image of window bars on a screen with the help of a convex lens. But in order to have the best image, his teacher suggested him to obtain the image of a distant tree. Where will the lens have to be moved in order to obtain a clear image?
The capacity of the lens to change its focal length as per need is called as
Retina of eye corresponds to which part of camera?
Power of lens is
When the distance between the eye-lens (crystalline-lens) and retina is more, the normal distance image is formed in front of the retina, such an eye defect is called as
For a specific glass lens f = 0.5 m. This is the only information given to the student. Which type of lens is given to him and what is its power?
In relaxed position of eye muscles, the focal length of healthy eye lens is about
The compound microscope is used to see
The point inside the lens on the principal axis through which light rays pass without changing their path is called
An optical instrument, in general, extends our range of vision by
............ helps the eye lens to adjust the focal length depending on the distance of the object by contracting or relaxing.
The minimum distance of an object from a human eye, at which it is clearly visible without stress on the eye is called
To obtain an image of the same size as that of an object using a convex lens, the object should be placed
Magnification of the lens is always positive for
If magnification of a lens is 10 then which of the following is correct?
A ray of light gets refracted ............... while entering the lens
............ is a combination of two convex lenses with small focal length.
For a myopic eye, the defect is cured by .............. .
For the same thickness of the lens, if the radius of curvature is increased, the focal length will
An object is kept at 20 cm from a convex lens of focal length 15 cm. The position of the image is
The farthest distance of an object from a human eye, at which it is clearly visible without stress on the eye is called
When two lenses are kept touching each other, the power of the combined lens is equal to
The direction of the ray passing through a lens changes because of the
A type of lens which has two spherical surfaces which are puffed up outwards is .............. .
Colour blindness indicates lack of
