Primary and Secondary Rainbow – Rankers Physics

Lens Makers Formula/ Len's Formula: Practice Problem & Solution

Assertion (A): Secondary rainbow is fainter than primary rainbow. Reason (R): Secondary rainbow is seen due to the scattering of primary rainbow through water molecules.  
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Lens Makers Formula/ Len's Formula. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true; secondary rainbows are fainter due to two internal reflections causing more light loss. Reason (R) is false; secondary rainbows result from light undergoing two internal reflections in raindrops, not scattering of a primary rainbow.

Leave a Reply

Your email address will not be published. Required fields are marked *

Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. Green light wavelength 5460 $\AA$ is incident on an air-glass interface. If the refractive index of glass is 1.5, the wavelength of light in glass would be ($c = 3 \times 10^8 ms^{-1}$) (1991)
2. Assertion (A): During sunset and sunrise sun appears to be red. Reason (R): During sunrise or sunset, sun emits electromagnetic radiations of comparatively higher wavelength only.  
3. Assertion (A): If one half of a mirror is covered by an opaque material, then only half image of the object is formed. Reason (R): By covering one half of the mirror, focal length of mirror will be halved.  
4. Assertion (A): A single lens cannot be free from chromatic aberration. Reason (R): When light passes through single lens dispersion must occur.  
5. An air bubble in a glass slab with refractive index $1.5$ (near normal incidence) is $5 cm$ deep when viewed from one surface and $3 cm$ deep when viewed from the opposite surface. The thickness (in cm) of the slab is: (2016 - II)