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

1

(a)

Presbyopia

(b)

Accommodation

(c)

Near sightedness

(d)

Far sightedness

The human eye forms the image of an object at its

1

(a)

Cornea

(b)

Iris

(c)

Pupil

(d)

Retina

The least distance of distinct vision for a young adult with normal vision is about

1

(a)

25 m

(b)

2.5 cm

(c)

25 cm

(d)

2.5 m

The change in focal length of eye lens is caused by action of

1

(a)

Pupil

(b)

Retina

(c)

Ciliary muscles

(d)

Iris

A person cannot see distinctly object kept beyond 2m.This defect can be corrected by using a lens of power

1

(a)

+0.5D

(b)

-0.5D

(c)

+0.2D

(d)

-0.2D

Which of the following phenomena of light are involved in the formation of a rainbow?

1

(a)

Reflection, refraction and dispersion

(b)

Refraction, dispersion and internal reflection

(c)

Refraction, dispersion and internal reflection

(d)

Dispersion, scattering and total internal reflection

Twinkling of stars is due to atmospheric

1

(a)

dispersion of light by water droplets

(b)

refraction of light by different layers of varying refractive indices

(c)

scattering of light by dust particles

(d)

internal reflection of light by clouds

The clear sky appears blue because

1

(a)

blue light  gets absorbed in the atmosphere

(b)

ultraviolet radiations are absorbed in the atmosphere

(c)

violet and blue lights get scattered more than lights of all other colours by the atmosphere

(d)

light of all other colours is scattered more than the violet and blue colour lights by the atmosphere

The danger signals installed at the top of tall buildings are red in colour.These can be easily seen from a distance because among all other colours, the red light

1

(a)

is scattered the most by smoke or fog

(b)

is scattered the least by smoke or fog

(c)

is absorbed the most by smoke or fog

(d)

moves faster in air

Which of the following statement is correct?

1

(a)

A person with myopia can see distant objects clearly

(b)

A person with hypermetropia can see nearby objects clearly

(c)

A person with myopia can see nearby objects clearly

(d)

A person with hypermetropia cannot see distant objects clearly

The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?

2

(a)

Why is a normal eye not able to see clearly the objects placed closer than 25 cm?

2

(a)

What happens to the image distance in the eye when we increase the distance of an object from the eye?

2

(a)

Explain why the planets do not twinkle.

2

(a)

Does myopia or hypermetropia imply necessary that the eye has partially lost its ability of accommodation?If not, what cause these defect of vision?

2

(a)

How are we able to see nearby and also the distant object clearly?

2

(a)

Draw a ray diagram showing through a prism when a narrow beam of white light is incident on one of its refracting surfaces.Also indicate the order of the colours of the spectrum obtained.

2

(a)

Is the position of a star as seen by us its true position? Justify your answer.

2

(a)

Why is the colour of the clear sky blue?

2

(a)

What is the difference in colours of the Sun observed during sunrise/sunset and noon?Give explanation for each

2

(a)