The Human Eye and the Colourful World — Class 10 Science PYQs

Consider the following statements in the context of human eye :
(a) The diameter of the eye ball is about $2.3\text{ cm}$.
(b) Iris is a dark muscular diaphragm that controls the size of the pupil.
(c) Most of the refraction for the light rays entering the eye occurs at the crystalline lens.
(d) While focusing on the objects at different distances the distance between the crystalline lens and the retina is adjusted by ciliary muscles.

The correct statements are -

The lens system of human eye forms an image on a light sensitive screen, which is called as :

In bifocal lenses used for the correction of presbyopia :

Consider the following statements in the context of human eye :
(a) The diameter of the eye ball is about $2.3\text{ cm}$.
(b) Iris is a dark muscular diaphragm that controls the size of the pupil.
(c) Most of the refraction for the light rays entering the eye occurs at the crystalline lens.
(d) While focusing on the objects at different distances the distance between the crystalline lens and the retina is adjusted by ciliary muscles.
The correct statements are –

For Q. Nos. 17 to 20, two statements are given – One labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below :
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.

Assertion (A) : The rainbow is a natural spectrum of sunlight in the sky.
Reason (R) : Rainbow is formed in the sky when the sun is overhead and water droplets are also present in air.

Q. Nos. 17 to 20 are Assertion – Reason based questions :
These questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below :

Assertion (A) : Myopic eye cannot see distant objects distinctly.
Reason (R) : For the correction of myopia converging lenses of appropriate power are prescribed by eye-surgeons.

Study the diagram given below and answer the questions that follow :

(i) Name the defect of vision represented in the diagram. Give reason for your answer.
(ii) List two causes of this defect.
(iii) With the help of a diagram show how this defect of vision is corrected.

(a) Define the term power of accommodation of human eye. Write the name of the part of eye which plays a major role in the process of accommodation and explain what happens when human eye focuses (i) nearby objects and (ii) distant objects.

OR

(b) Draw a ray diagram to show the formation of a rainbow in the sky. On this diagram mark A - where dispersion of light occurs, B - where internal reflection of light occurs and C - where refraction of light occurs. List two necessary conditions to observe a rainbow.

A narrow beam, PQ of white light is passing through a glass prism ABC as shown in the diagram.

Draw a ray diagram to show the emergent beam as it falls on the screen DE. Also write the phenomenon involved and its cause. Using the second law of refraction state which colour of light must have the highest value of refractive index amongst seven visible colours of light. Justify your answer.