English Medium Class 10 - CBSE Question Bank Solutions for Science

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

Your friend can read a book perfectly well but cannot read the writing on blackboard unless she sits on the front row in class. 

 Is she short-sighted or long-sighted?

Your friend can read a book perfectly well but cannot read the writing on blackboard unless she sits on the front row in class. 

 What type of lenses-converging or diverging-would an optician prescribe for her?

A man can read the number of a distant but clearly but he finds difficulty in reading a book. 

 From which defect of the eye is he suffering?

A man can read the number of a distant but clearly but he finds difficulty in reading a book.  

What type of spectacle lens should he use to correct the  defect?

A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard. 

 Name the type of defect he is suffering from.

A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard. 

 How can this defect by corrected?

What are the two most common defects of vision (or defects of eye)? How are they corrected?

Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How does it help?

Name the defect of vision which can be corrected by a converging lens. Show clearly by a ray diagram how the lens corrects the defect.

Name the defect of vision which can be corrected by a diverging lens. Show clearly by a ray diagram how the lens corrects the defect.

Explain with the help of labelled ray diagram, the defect of vision called myopia and how it is corrected by a lens.

Explain with the help of labelled ray-diagram, the defect of vision called hypermetropia, and hot it is corrected by a lens. 

A person suffering from the eye-defect myopia (short-sightedness) can see clearly only up to a distance of 2 metres. What is the nature and power of lens required to rectify this defect?

The near-point of a person suffering from hypermetropia is at 50 cm from his eye. What is the nature and power of the lens needed to correct this defect? (Assume that the near-point of the normal eye is 25 cm).

What is short-sightedness? State the two causes of short-sightedness (or myopia). With the help of ray diagrams, show:
(i) the eye-defect short-sightedness.
(ii) correction of short-sightedness by using a lens.

 A person having short-sight cannot see objects clearly beyond a distance of 1.5 m. What would be the nature and power of the corrective lens to restore proper vision?

 What is long-sightedness? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show:
(i) the eye-defect long-sightedness.
(ii) correction of long-sightedness by using a lens.

 An eye has a near point distance of 0.75 m. What sort of lens in spectacles would be needed to reduce the near point distance to 0.25 m? Also calculate the power of lens required. Is this eye long-sighted or short-sighted? 

An eye has a far point of 2 m. What type of lens in spectacles would be needed to increase the far point to infinity?  Also calculate the power of lens required. Is this eye long-sighted or short-sighted?