Class 10 Science MCQs

Chapter 11 The Human Eye and the Colourful World

Topics: The Human Eye and the Colourful World Defects in eyes myopia hypermetropia persbyopia astigmatism cataraet and their corrections. Dispersion of light prizm

2256

1. Which of the following lenses would you prefer to use while reading small letters found in a dictionary?

2240

2. The change in focal length of an eye lens is caused by the action of the:

2263

3. Myopia can be corrected by using.............. lens.

2244

4. The twinkling of a star is due to ................ of light.

2257

5. The human eye can focus object at different distances by adjusting the focal length of eyelens. This is due to .......

2242

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

2251

7. The colour of 'danger' signal is.......

2237

8. The colour of sky is blue due to:

2243

9. The twinkling of a star is due to ................ of light.

2259

10. Main cause of early sunrise and delayed sunset is ................. of light.

2262

11. The eye defect in which eyelens of a person becomes cloudy is:

2247

12. The colour of the sunset is red due to:

2246

13. Main cause of advanced sunrise and delayed sunset is:

2260

14. In hypermetropia, we cannot see:

2264

15. Hypermetropia can be corrected by using................ lens.

Basic Facts The Human Eye and the Colourful World


Eye forms an image of an object at the retina. For a normal eye the near point is 25cm and far point is at infinity

Following defects are commonly observed in eyes
(i) Myopia: Myopia is also known as short sightedness or near sightedness.Aperson suffering from myopia can see the nearby objects clearly but distant objects are not very clear or distinct. One of the main reason for this defect is the increase in the curvature of eye lens. Therefore, the image of a far obejct is formed infront of the retina while the image of nearby objects is formed at retina.
To correct the defects of short sightedness a concave lens of apporpriate power is placed before the eye.
(ii) Hypermetropia: Hypermetropia is also known as long sightednessorfar sightedness.Aperson suffering from hypermetropia is able to see distant objects clearly. Such persons connot see the nearby objects clearly.
o correct the defect of long sigthedness a convex lens of appropriate power is placed before the eye.
(iii) Presbyopia: The flexibility of eye lens and its surrounding fibrous structure decreases with age and thereby the accomdation power of eye reduces. This makes it difficult for people to clearly see the nearby objects.
(iv) Astigmatism: Astigmatism is beacuse of irregular curvature of the cornea and people of all ages can be affected by this problem.Aperson with astigmatism cannot clearly see horizontal and vertical lines at the same distance simultaneouly. Cylindrical lenses are used to correct this defect of eye.
(v) Cataraet With aging thetransperancy andflexibility of eye lens reduces. The eye stalls reflecting light because of this reduction in transperancy and the object is not clearly visible to such an eye. This defect is known as cataract