human eye and Light

Change in focal length of an eye lens is caused by the action of the

• Pupil

• Retina

• Ciliary muscles

• Iris

The human eye can focus objects at different distances by adjusting the focal length of the eye lens . This is due to

• Presbyopia

• Accommodation

• Near-sightedness

• Far-sightedness

A person with a myopic eye cannot see objects beyond 1.2 metres distinctly . What should be the type of corrective lens used to restore proper vision

• Concave lens

• Convex lens

• Bifocal lens

• Concave mirror

Name the corrective lens used for hypermetropia

• Concave lens

• convex lens

• Bifocal lens

• Diverging lens

Function of the optic nerve is is

• Transfer the signals to brain

• Image formation

• sensation of vision

• Controls the light entering the human eye

Near and far points of a young person normal eye respectively are---------

• 0 and infinity

• 0 and 25 cm

• 25 cm and infinity

• 25 cm and 150 cm.

The ability of eye lens to adjust its focal length to form a sharp image of the object at varying distances on the retina is called -------------

• Power of observation of the eye

• Power of adjustment of the eye

• Power of accommodation of the eye

• Power of enabling of the eye

Assertion: The near-point of a hypermetropic eye is more than 25 cm away.

Reason: Hypermetropia is corrected using spectacles containing concave lenses.

• Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.

• The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.

• Assertion is true but the Reason is false

• The statement of the Assertion is false but the Reason is true.

When white light enters a prism, it gets split into its constituent colours. This is due to

• different refractive index for different wavelength of each colour

• each colours has same velocity in the prism.

• prism material have high density.

• Scattering of light

The air layer of atmosphere whose temperature is less then the hot layer behave as optically

• denser medium

• rarer medium

• inactive medium

• either denser or rarer medium