............ is a combination of two convex lenses with small focal length.

An optical instrument, in general, extends our range of vision by

The ............. cells respond to the colour and give information about the colour of the object to the brain.

When two lenses are kept touching each other, the power of the combined lens is equal to

Principal focus of a magnifying glass is

The farthest distance of an object from a human eye, at which it is clearly visible without stress on the eye is called

Distance between optical centre and centre of curvature is called as .............. ..

A ............... lens always produces virtual and diminished image.

A type of lens which has two spherical surfaces which are puffed up outwards is .............. .

For a myopic eye, the defect is cured by .............. .

For the normal human eye, minimum distance of distinct vision is ............. cm.

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?

A focal length of a lens is 20 cm. What is power of a lens in dioptre?

Power of lens is

At what distance a watch maker must hold his lens from the watch?

A person suffering from hypermetropia

In relaxed position of eye muscles, the focal length of healthy eye lens is about

The capacity of a lens to converge or diverge incident rays is called .............. of the lens.

According to Cartesian sign conventions, all the distances are measured from the

People suffering from both myopia and hypermetropia, needs ............. lens

If magnification of a lens is 10 then which of the following is correct?

The capacity of the lens to change its focal length as per need is called as

Bifocal lens is required to correct ............... defect.

The point inside the lens on the principal axis through which light rays pass without changing their path is called

An object is kept at 20 cm from a convex lens of focal length 15 cm. The position of the image is

The colour of the eye is determined by

A type of lens which is thinner at centre than at edges is........ .

Colour blindness indicates lack of

A convex lens of short focal length held very close to the eye, to observe minute objects clearly is called as

The final image produced by a simple microscope is

The minimum distance of an object from a human eye, at which it is clearly visible without stress on the eye is called

A ray of light gets refracted ............... while entering the lens

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

Which of the following is wrong? Here M represents magnification of a lens.

When we see an object, the image formed on the retina is

To obtain an image of the same size as that of an object using a convex lens, the object should be placed

Retina of eye corresponds to which part of camera?

Magnification of the lens is always positive for

The compound microscope is used to see

The direction of the ray passing through a lens changes because of the

There is a small hole of changing diameter at the centre of the iris which is called

Defective refraction by the lenses causes

The image obtained while finding the focal length of convex lens is

A convex lens forms a virtual image of an object placed ............. .

An object is placed at a distance of f/2 from a convex lens of focal length f. The image will be

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?

The power of spectacles for hypermetric person

For the same thickness of the lens, if the radius of curvature is increased, the focal length will

............ helps the eye lens to adjust the focal length depending on the distance of the object by contracting or relaxing.

The focal length of a concave lens, according to Cartesian sign conventions is