Power of lens is

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

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

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?

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

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

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

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

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

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

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

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

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

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

A person suffering from hypermetropia

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

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

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

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

Retina of eye corresponds to which part of camera?

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

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

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

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

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

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

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

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

Defective refraction by the lenses causes

Magnification of the lens is always positive for

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

The power of spectacles for hypermetric person

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

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

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

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

Principal focus of a magnifying glass is

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

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

The colour of the eye is determined by

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

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

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

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

The compound microscope is used to see

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?

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

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