Case Study 3 - Formation of rainbow

 

Case based/Passage-based Questions
 

Answer the questions that follow on the basis of your understanding of the following paragraph and the related studied concepts:
 

A rainbow is one of the most spectacular natural light shows observed in the sky. A number of scientist and mathematician including Aristotle, Bacon, Theodoric, Descartes, Newton, Young, Airy and Mie have worked on the explanation of various observations on rainbows.

To understand the formation of rainbow one should actually study the refraction, internal reflection dispersion and total deviation of white light by the spherical water drop.

A rainbow is produced when sunlight falls and gets diverted to the eyes of the observer due to a large number of water droplets in the sky on a rainy day.

In addition to primary Rainbow there is a secondary rainbow. It occurs in the same manner as the primary rainbow but due to two internal reflections. In nature we can observe only primary and secondary rainbows. Higher order rainbows are never seen since they are weaker than (i) the background sky brightness (ii) the light reflected from the outside surface of the drops and (iii) the light transmitted through the process with no internal reflections.

 

Q1            What is refraction?

(a) bouncing back of light in the same medium

(b) change in the direction and speed of light when light travels from one optical medium to the other.

(c) splitting of light into its components colors - VIBGYOR

(d) spreading of light in all direction

Q2.         The two essential conditions for observing a rainbow are:

 1. The sun needs to be behind the viewer.

2. Rain, fog or water droplets must be in front of the viewer.

3. The viewer must be present at the spot.

(a) none of the above

(b) all of the above

(c) 1 and 2 only

(d) 3 only

Q3. What is the shape of a rainbow?

(a) arc shaped

(b) circular

(c) semi-circular

(d) straight line

Q4. Which color of light travel fastest in the water droplet?

(a) Red

(b) violet

(c) green

(d) yellow