Solutions of The Human Eyes And The Colorful Wor (Page No- 279) - Physics By Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Lakhmir Singh Physics Class 10 Solutions Page No:279

Question 1: Name one of the common defects of vision and the type of lens used to remove it.

Solution : Defect: Myopia; Corrected by using concave lens.

Question 2: Name the defect of vision in a person :
 (a) whose near point is more than 25 cm away.
 (b) whose far point is less than infinity

Solution : (a) Hypermetropia
(b) Myopia

Question 3: Which defect of vision can be rectified :
 (a) by using a concave lens ?
 (b) by using a convex lens ?

Solution : (a) Myopia
(b) Hypermetropia

Question 4: What type of lens is used to correct
 (a) hypermetropia
 (b) myopia ?

Solution : (a) Convex lens
(b) Concave lens

Question 5: What is the other name for
 (a) myopia (b) hypermetropia ?

Solution : (a) Near Sightedness
(b) Far Sightedness

Question 6: What is the scientific name of
 (a) short-sightedness, and
 (b) long-sightedness ?

Solution : (a) Myopia
(b) Hypermetropia

Question 7: What kind of lens is used to correct (a) short-sightedness (b) long-sightedness ?

Solution : (a) Concave lens
(b) Convex lens

Question 8: State whether the following statement is true or false :

Short-sightedness can be cured by using a concave lens.

Solution : True

Question 9: Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.

Solution : Presbyopia

Question 10: Name the defect of vision which makes the eye-lens cloudy resulting in blurred vision.

Solution : Cataract

Question 11: What is the other name of old age hypermetropia ?

Solution : Presbyopia

Question 12: Name any two defects of vision which can be corrected by using spectacles.

Solution : (a) Myopia
(b) Hypermetropia

Question 13: Name one defect of vision (or eye) which cannot be corrected by any type of spectacle lenses.

Solution : Cataract

Question 14: Name the body part with which the terms myopia and hypermetropia are connected.

Solution : Eye

Question 15: What is the far point of a person suffering from myopia (or short-sightedness) ?

Solution : Less than infinity.

Question 16: Where is the near point of a person suffering from hypermetropia (or long-sightedness) ?

Solution : The near point of a person suffering from hypermetropia is farther away from the normal near point (25 cm).

Question 17: Your friend can read a book perfectly well but cannot read the writing on blackboard unless she sits on the front row in class.
 (a) Is she short-sighted or long-sighted ?
 (b) What type of lenses-converging or diverging-would an optician prescribe for her ?

Solution : (a) Short-sighted
(b) Diverging lenses

Question 18: A man can read the number of a distant bus clearly but he finds difficulty in reading a book.A man can read the number of a distant bus clearly but he finds difficulty in reading a book.
 (a) From which defect of the eye is he suffering ?
 (b) What type of spectacle lens should he use to correct the defect ?

Solution : (a) Hypermetropia (Long Sightedness)
(b) Convex lens

Question 19: A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard.
 (a) Name the type of defect he is suffering from.
 (b) How can this defect by corrected ?

Solution : (a) Myopia (Short – Sightedness)
(b) Concave lens

Question 20: Complete the following sentences :
 (a) A short-sighted person cannot see ……….. objects clearly. Short-sightedness can be corrected by using
 ……… lenses.
 (b) A long-sighted person cannot see…………. objects clearly. Long-sightedness can be corrected by using
 ………. lenses.

Solution : (a) distant, concave
(b) nearby, convex