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Figure shows a ray of light as it travels from medium A to medium B. Refractive index of the medium B relative to medium A is (a) Root 3 / Root 2 (b) 2 / 3 (c) 1/ 2 (d) 2

Answer: √3/√2 Refractive Index of B with respect to A The ratio of the sine of the angle of incidence to the sine of the angle of refraction... View Article

Under which of the following conditions a concave mirror can form an image larger than the actual object? (a) When the object is kept at a distance equal to its radius of curvature (b) When an object is kept at a distance less than its focal length (c) When an object is placed between the focus and centre of curvature (d) When an object is kept at a distance greater than its radius of curvature

Answer: (c) When an object is placed between the focus and centre of curvature The image will be located beyond the centre of curvature if the... View Article

A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is (a) – 30 cm (b) – 20 cm (c) – 40 cm (d) – 60 cm

Answer: (b) - 20 cm Given parameters size of object (O) = + 10.0 mm = + 1.0 cm (as, 1 cm = 10 mm) Size of Image (I) = 5.0 mm = 0.5 cm Image... View Article

How does refraction take place in the atmosphere? Why do stars twinkle but not the planets?

Answer: The atmosphere is made up of several layers. The upper layer is optically rare, but the bottom layer is optically denser. Refraction... View Article

How can we explain the reddish appearance of the sun at sunrise or sunset? Why does it not appear red at noon?

Answer: During sunrise, the light rays coming from the Sun have to travel a greater distance in the earth’s atmosphere before reaching our... View Article

Explain the refraction of light through a triangular glass prism using a labelled ray diagram. Hence define the angle of deviation.

Answer: The angle of deviation is defined as the angle which is obtained from the difference between the angle of incidence and the angle of... View Article

When do we consider a person to be myopic or hypermetropic? Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected?

Answer: Myopia is a condition where a person cannot see distant objects clearly and he can see nearer objects clearly. Hypermetropia is a... View Article

Explain the structure and functioning of the human eye. How are we able to see nearby as well as distant objects?

Answer: The human eye is one of the most valuable and sensitive sense organs. It enables us to see the wonderful world and the colours around... View Article

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

Answer: During sunrise, the light rays coming from the Sun have to travel a greater distance in the earth’s atmosphere before reaching our... View Article

Why do we see a rainbow in the sky only after rainfall?

Answer: Rainbow is caused by the dispersion of sunlight by tiny water droplets, present in the atmosphere. A rainbow is always formed in a... View Article

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

Answer: No, that is not the truth. We see the apparent position of the star because we know there are many layers in the atmosphere, so... View Article

Draw a ray diagram showing the dispersion 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.

Answer: VIBGYOR (Violet colour, Indigo colour, Blue, colour, Green colour, Yellow colour, Orange colour & red colour). Violet – 4000... View Article

How will you use two identical prisms so that a narrow beam of white light incident on one prism emerges out of the second prism as white light? Draw the diagram.

Answer: By placing two identical prisms inverted with respect to the other we get a narrow beam of white light incident on one prism emerges... View Article

A person needs a lens of power –4.5 D for correction of her vision. (a) What kind of defect in vision is she suffering from? (b) What is the focal length of the corrective lens? (c) What is the nature of the corrective lens?

Answer: (a) Myopia Myopia is the inability of an eye in viewing long distant objects. The image in this case is formed before the retina. For... View Article

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

Answer: Our eyes can focus on the images from a varied distance by changing the focal length of the lens. The action of the Ciliary muscle... View Article

A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw ray diagram for the correction of this defect.

Answer: If a student cannot see the blackboard distance to her she is suffering from Myopia. Hence doctor advises a concave lens of suitable... View Article

Draw ray diagrams each showing (i) myopic eye and (ii) hypermetropic eye.

Answer: Myopia is a condition where a person cannot see distant objects clearly and he can see nearer objects clearly. Hypermetropia is a... View Article

Which of the following statement is correct? (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

Answer: (c) A person with myopia can see nearby objects clearly Myopia is a condition where a person cannot see distant objects clearly and he... View Article

The focal length of the eye lens increases when eye muscles (a) are relaxed and the lens becomes thinner (b) contract and lens becomes thicker (c) are relaxed and the lens becomes thicker (d) contract and lens becomes thinner

Answer: (a) are relaxed and the lens becomes thinner When the muscles are relaxed, the lens becomes thin. Thus, its focal length increases.... View Article

When light rays enter the eye, most of the refraction occurs at the (a) crystalline lens (b) outer surface of the cornea (c) iris (d) pupil

Answer: (b) outer surface of the cornea When light rays enter the eye through a thin membrane, the cornea forms a transparent bulge on the... View Article

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