Class 10 Science Chapter 11 MCQ

Iris is a flat, colored, ring shaped membrane behind the cornea of the eye. There is a hole in the middle of the Iris which is called pupil of the eye. Therefore, pupil is a hole in the middle of the Iris.

The sun appears red at sunset because, at that time, the sun is near the horizon and, therefore, sunlight has to travel through a greater thickness of the earth’s atmosphere.

the space between cornea and eye lens is filled with a watery liquid called “aqueous humor”. And the space between eye lens and retina is filled with transparent jelly like substance called vitreous humour which supports the back of the eye.

The sky appears blue because some of the blue component of sunlight is scattered by the gas molecules (nitrogen and oxygen) present in the air.

Here, all the statements are correct. Hence, your answer will be option [D].

The sun appears red at sunset not because of the atmospheric refraction of light but because of the scattering effect of light.

The twinkling of star is due to atmospheric refraction of light of stars. These lights, on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth. The path of rays of light coming from the distant star goes on varying slightly, the apparent position of the star fluctuates and the amount of starlight entering the eye flickers. The star sometimes appears brighter and at some other time, fainter gives us the twinkling effect.

the whole purpose of using a concave lens here is to reduce the converging power of the eye-lens. The concave lens used here decreases the converging power of the eye-lens and helps in forming the image of distant object on the retina of the myopic eye.

As the person has the eye defect, myopia, therefore, a concave lens has to be used whose focal length will be, f = – 2 m (using sign convention). Thus, Power, P = 1/f (where, f is focal length in metre) = 1/- 2 = -0.5 D

As the light from a far-off star comes towards the earth, it bends towards the normal because the air is denser closer to the surface of the earth.

The whole purpose of using a convex lens is to increase the converging power of the eye-lens. The convex lens used in spectacles increase the converging power of islands and helps in forming the image of a nearby object on the retina of the eye.

the propagation of light of different colours of white light in air or vacuum move with the same speed but different wavelengths and frequencies.

Stars twinkle because they are far away. The planets do not twinkle at night because they are nearer to the earth.

Here, all the statements are correct. Hence, your answer will be option [D].

The bluish color of water in deep sea is due to scattering of light as the very fine particles in water scatter mainly blue light. The red, green, orange and yellow having longer wavelengths are absorbed more strongly by water then blue which has shorter wavelength. So, when white light from the sun enters the sea, it is mostly the blue that gets returned.

Actually, in refraction through a glass prism the emergent ray is deviated from its original direction by a certain angle. And we say that light rays get deviated on passing through a glass prism. Therefore, in refraction through a glass prism, the emergent ray is not parallel to the incident ray. Q.29. When light rays enter the eye, most of the refraction occurs at the

When the light rays enters the eye through a thin membrane, forms the transparent bulge on the front surface of the eyeball, called the cornea. Most of the refraction for the light rays entering the eye occurs at this outer surface of the cornea.

If a man driving a car can see a distant road sign distinctly but cannot read the odometer on the dashboard of the car clearly, it suggests that the near point of his eyes has receded.

Here, all the statements are correct. Hence, your answer will be option [D].

The seven colours of the spectrum can be denoted by the word VIBGYOR. Where V stands for violet, I for indigo, B for blue, G for green, Y for yellow, O for orange and R for red. Note: These colours in the order of increasing frequency (but decreasing wavelengths) are: red, orange, yellow, green, blue, indigo and violet. Red has the maximum wavelength.

The nitrogen and oxygen gas molecules present in the atmosphere are smaller than the wavelength range of visible light. So, when light coming from the sun hits this very small air molecules, it behaves differently. Since, the different colours of white light have different wavelengths, so they are affected differently. The lower wavelengths lights (blues) are scattered much more by the air molecules but the higher wavelengths lights (reds) are scattered much less.

The term ‘accommodation’ as applied to the eye refers to its ability to vary the focal length of the lens.

The human eye possesses the power of accommodation to focus on objects at different distances.

As the far point of the eye is closer to him than normal, he can see nearby objects, but not distant objects, clearly.

Having two eyes gives a person a wider field of view.