NCERT Class 10: Science-Intext Solutions
Chapter 11-The Human Eye and the Colourful World-Intext Solutions
NCERT Science Book Page Number: 190
Q.1. What is meant by power of accommodation of the eye?
Ans. The ability of the eye lens to adjust its focal length, so as to clearly focus rays coming from distant as well near objects on the retina, is called the power of accommodation of the eye.
Q.2. A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision?
Ans. A person with a myopic eye should use a concave lens of focal length 1.2 m so as to restore proper vision.
Q.3. What is the far point and near point of the human eye with normal vision?
Ans. The near point of the eye is the minimum distance of the object from the eye, which can be seen distinctly without strain. For a normal human eye, this distance is 25 cm.
The far point of the eye is the maximum distance to which the eye can see the objects clearly. The far point of the normal human eye is infinity.
Q.4. A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?
Ans. The student is suffering from myopia or short-sightedness. The defect can be corrected by the use of concave (diverging) lens of an appropriate power.