CBSE Class 10 - Physics - The Human Eye and Colourful World (Very Short Q and A)(#cbsenotes)

The Human Eye and Colourful World

Very Short Q and A


Question 1: Name the essential parts of a human eye.

Answer: Cornea, Iris, Pupil, eye lens, ciliary muscles and retina.


Question 2: What is cornea??

Answer: Spherical membrane covering the front of the eye


Question 3: Which liquid fill the space behind the cornea?

Answer: Aqueous humour


Question 4: Which liquid fills the space between lens and retina?

Answer: vitreous humour


Question 5: How is the eye lens held in its position?

Answer: By Ciliary muscles which hold the eye in position.




Question 6: What is iris?

Answer: The coloured diaphragm between the cornea and lens


Question 7: Which part of the eye controls the amount of light entering the eye?

Answer: The pupil


Question 8: What is eye lens made of?

Answer: It is made of a jelly-like material
 

Question 9: How is the sense of vision carried from the eye to the brain?

Answer: Through the optic nerve


Question 10: What is a blind spot answer the point?

Answer:  A spot on a retina at which the optic nerve leaves the eye.


Question 11: Why is blind spot so called?

Answer: An image formed at this point is not sent to the brain.


Question 12: What is the number of receptors contained in the retina?

Answer: It contains more than 125 million receptors.


Question 13: What is meant by accommodation of eye?

Answer: The ability of the eye lens to adjust its focal length is called accommodation.


Question 14: What is the other name of accommodation of an eye?

Answer: Power of accommodation


Question 15: What is meant by the far point?

Answer: The farthest point up to which eye can see clearly is called the far point of the eye.


Question 16: What is the near point of a normal human eye?

Answer: The nearest point up to which an eye can see clearly is called the near point of the eye.


Question 17: What is meant by the least distance of distinct vision of a normal human eye?

Answer: About 25 cm from the eye


Question 18: What is meant by least distance of distinct vision?

Answer: It is the minimum distance up to which eye can see clearly and is called the least distance of distinct vision


Question 19: What is the least distance of distinct vision and human normal human eye?

Answer: It is around 25.


Question 20: What are the defects of vision of human eye?

Answer:
① myopia also called short-sightedness
② hypermetropia also called long sightedness
③ astigmatism


Question 21: What is near-sightedness?

Answer: It is the defect of the eye in which a person can the nearby objects clearly bu cannot see the far away objects clearly.


Question 22: What is the other name of near-sightedness?

Answer: Myopia


Question 23: Give one cause of near-sightedness?

Answer: Decrease of the focal length of the eye lens.


Question 24: How is nearsightedness corrected?

Answer: Using a concave lens of suitable focal length.


Question 25: Where is the image formed in an eye suffering from near-sightedness?

Answer: The image formed in front of a retina.


Question 26: What is long sightedness?

Answer: It is a defect of the eye in which a person can see distant objects clearly but cannot see nearby objects clearly.


Question 27: Give one reason of long sightedness.

Answer: Increase of the focal length of a lens


Question 28: Where is the image formed in an eye suffering from long sightedness?

Answer: The image formed behind the retina.


Question 29: How is long sightedness corrected?

Answer: By using a convex lens of suitable focal length.


Question 30: What is astigmatism?

Answer: It is a defect in which a person cannot see in all directions equally well.


Question 31: What is presbyopia?

Answer: Presbyopia is that effect of human eye due to which an old person cannot read and write comfortably.


Question 32: What is the other name of presbyopia?

Answer:  Its other name is an old sight.


Question 33: Name the colours of a visible spectrum.

Answer: The various colours are violet, indigo, blue, green, yellow, orange and red (VIBGYOR).


Question 34: What is twinkling of stars due to?

Answer: Due to refraction of light by Earth's atmosphere.


Question 35: Define Dispersion of white light.

Answer: Splitting of white light into various constituents is called Dispersion of light


Question 36: What kind of lens is used in spectacles of a person suffering from myopia?

Answer: Concave lens


Question 37: What would have been the colour of sky if there was no atmosphere

Answer: it would be dark.


Question 38: Name the two phenomena involved in the formation of a rainbow?

Answer: (i) dispersion and (ii) total internal reflection