Question

Pick the wrong answer in the context with rainbow.

• A. When the light rays undergo two internal reflections in a water drop, a secondary rainbow is formed.
• B. The order of colours is reversed in the secondary rainbow.
• C. An observer can see a rainbow when his front is towards the sun.
• D. Rainbow is a combined effect of dispersion, refraction and reflection of sunlight.

Answer 1

The Correct Option is C

To solve this question, we need to understand the phenomenon of rainbows and how they are observed.

1. Understanding Rainbow Formation: A rainbow is created by the dispersion, refraction, and reflection of sunlight in water droplets. When light enters a water droplet, it bends (refraction), reflects off the inside surface of the droplet, and then exits the droplet, bending again (refraction). This process separates the light into its component colors, forming a rainbow.
2. Primary and Secondary Rainbows:
   • A primary rainbow occurs when there is one reflection inside the droplet. The sequence of colors from top to bottom typically follows the VIBGYOR order (Violet, Indigo, Blue, Green, Yellow, Orange, Red).
   • A secondary rainbow is formed when light undergoes two internal reflections. The color order is reversed (ROYGBIV) because of the additional reflection.
3. Observational Position: A rainbow is visible when the observer's back is towards the Sun and the front is towards the region of the sky with the water droplets. Thus, the statement "An observer can see a rainbow when his front is towards the sun" is incorrect, as it contradicts the necessary condition for viewing a rainbow.

Based on the concepts above, the correct answer is that the assertion that an observer can see a rainbow when facing the sun is incorrect. Instead, the observer must be facing away from the sun to properly witness the phenomenon of a rainbow.

Here's a summary of why the correct option is chosen:

1. The processes involved in the formation of a rainbow (dispersion, refraction, reflection) are correctly stated in the options and the question.
2. The reversal of color order in secondary rainbows is also accurately stated.
3. The observation condition is incorrectly stated in the option marked as the correct answer, which is why it is chosen as the wrong answer in the context of the question.