Cls 10 Sci Chp 11 prvs aprd quns

       Class 10 Science

Previous Years  Appeared Questions and Answers    

  Chapter 11 Human Eye and Colorful World     

           Multiple Choice Questions     

1. The sky as seen from the surface of the moon appears dark because, (Sep - 2020)

(A) only a little of the blue and violet colours are scattered

(B) all the colours are absorbed by the atmosphere present in the moon

(C) all the colours are scattered Total

(D) atmospheric particles needed to scatter the light are not present.

Ans. : (D) atmospheric particles needed to scatter the light are not present.             

  One Mark Questions              

1. A student sitting in the last bench has difficulty in reading the blackboard writing. Which is the defect of vision the student has ? How can it be corrected ? (Sep - 2020)

Ans. :

★ The student is suffering from Myopia.

★ This defect is corrected by using a concave lens of suitable power.

2. What is the function of pupil of the human eye ? (June -2019)

Ans:

It controls the amount of light that enters the eye. 

      Two Marks Questions            

1. Draw the diagram showing the hypermetropic eye. (June - 2020)

Ans. : 

2. (i) What is Tyndall effect ?

(ii) Name the colour that bends the least and the colour that bends the most when white light is dispersed by a prism. (June 2019)

Ans:

(i) The phenomenon of scattering of a beam of light by colloidal particles, when passed through a colloidal solution, is called the Tyndall effect”.

(ii) The light that bends the least is red colour and the light that bends the maximum is violet colour light.

                          

3. (i) What is meant by the power of accommodation of the eye ?

(ii) What are the far point and near point of the human eye with normal vision ? (June 2019)

Ans: 

(i) Power of accommodation is the ability of the eye lens to focus near and far objects clearly on the retina by adjusting its focal length.

(ii) For a young adult with a normal vision, the near point is about 25 cm and the far point of the eye is at infinity. A normal eye can see objects clearly that are between 25 cm and infinity.

4. What is hypermetropia or far-sightedness ? Name the type of lens used to correct it. (June 2019)

Ans:

Hypermetropia or far-sightedness is a defect of the eye in which nearby objects appear blurry but distant objects are clear. It can be corrected using a convex lens of suitable focal length.

5. Draw the diagram to represent the recombination of the spectrum of white light. Label the following parts : (i) Prism (ii) Screen. (June 2019)

Ans:

              Three Marks Questions            

1. a) Draw the diagram to show the recombination of the spectrum of white light and label the following parts.

b) The ray of light that bends the most The ray of light that bends the least. (Sep - 2020)

Ans:

Total Recombination of spectrum of white light :

                Five Marks Questions              

1. Explain the experiment conducted by Newton to show that white light contains seven colours. Sun appears red in colour during sunrise but appears white at noon. Explain with the reasons. (June - 2020)

Ans. :

★ Isaac Newton was the first to use a glass prism to obtain the spectrum of sun light.

★ He tried to split the colours of the spectrum of white light further by using similar prism. He could not get any more colours.

★ He then placed a second prism (identical) in an inverted position with respect to the first prism. This allowed all the colours of the spectrum to pass through the second prism.

★ He found a beam of white light emerging from the other side of the second prism. This observation gave Newton the idea that the sun light is made up of seven colours.

★ Light from the sun near the horizon passes through thicker layers of air and larger distance in the earths atmosphere before reaching our eyes.

★ Near the horizon most of the blue light and shorter wavelengths are scattered away by the particles.

★ Therefore the light that reaches our eyes is of longer wavelength. This gives the reddish appearance to the sun.

★ However light from the sun overhead would travel relatively shorter distance.

★ At noon, the sun appears white as only a little of the blue and violet colours are scattered.