Class 10 Science Chapter 10 MCQ

The student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his book because he is suffering from hypermetropia or farsightedness. He can see distant objects clearly but cannot see nearby objects distinctly. Note: Hypermetropia may have blurred vision to a person when looking at objects close to them and clearer vision when looking at objects in the distance.

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 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].

Rainbow is caused by dispersion, refraction and internal reflection of sunlight by tiny water droplets, present in the atmosphere and always formed in a direction opposite to that of the sun. The water droplets act like a small prism. They refract and disperse the incident sunlight, then reflect it internally and finally refract it again when it comes out of the raindrop.

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

When the eye is looking at a distant object, the eye is said to be unaccommodated because it is the relaxed state of the eye.

The clear sky appears blue is due to Rayleigh scattering of sunlight. The molecules in the air scatter blue light from the sun more than they scatter red light.

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 danger signals installed at the top of tall buildings are red in colour because among all other colours, red colour is scattered the least by smoke of fog. This is primarily because wavelength of red colour is the largest. Thus, it can be easily seen from a distance.

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.

The focal length of the eye lens increases when eye muscles relaxed and becomes thinner. The sharp image of the distant object is formed at the retina. This enables us to focus accurately on distant objects.

A person with myopia can see nearby objects clearly. While a person with hypermetropia can see distant objects clearly.

The thickness of the eye lens is increased to focus the image of a nearby object on the retina of the eye.

The eye lens becomes thicker to focus on nearby objects and thinner to focus on distant objects.

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.

Animals of prey have two eyes on the sides of their head. This gives them a wide field of view and allows them to see the approach of potential predators.