Statement I: Occasionally we see two rainbows together, the primary rainbow with another less intense secondary rainbow about 10 degrees away
Statement II: The secondary rainbow appears due to refraction after a reflection of sunlight from the water droplets
Statement Analysis: Rainbow Formation
This question asks about the formation and observation of primary and secondary rainbows.
Statement I Evaluation: Observation of Double Rainbows
- Statement I correctly observes that sometimes two rainbows are visible: a brighter primary rainbow and a fainter secondary rainbow.
- It also accurately notes that the secondary rainbow appears roughly 10 degrees away from the primary one. The actual angular separation is about 9 degrees.
- Therefore, Statement I is true.
Statement II Evaluation: Cause of Secondary Rainbow
- Statement II claims the secondary rainbow appears due to refraction after *a* reflection of sunlight from water droplets.
- While refraction and reflection are involved, the secondary rainbow specifically forms due to *two* internal reflections of sunlight within the water droplets, followed by refraction upon exiting.
- The primary rainbow, in contrast, is formed by only *one* internal reflection.
- Because Statement II omits the crucial detail of *two* reflections required for the secondary rainbow and only mentions "a reflection", it does not accurately describe the specific mechanism causing the secondary rainbow.
- Therefore, Statement II, while containing elements of truth about optical processes, is not a correct or complete explanation for the secondary rainbow's specific formation. It's considered false in the context of being a correct explanation.
Conclusion
Both statements describe aspects related to rainbows. Statement I is factually correct about the observation. Statement II describes optical processes involved but fails to capture the specific mechanism (two reflections) that distinguishes the secondary rainbow. Thus, Statement II is not the correct explanation for why the phenomenon described in Statement I occurs.
Correct Answer: Both statements are individually true, but Statement II is NOT the correct explanation of Statement I.
Important Questions from Refraction and Reflection
A convex lens of focal length f will form a magnified real image of an object, if the object is placed.
A ray of light travelling in the direction \(\frac{1}{2} (\hat i + \sqrt 3 \hat j)\) is incident on a plane mirror. After reflection it travels along the direction \(\frac{1}{2} (\hat i - \sqrt 3 \hat j)\) The angle of incidence is:
Twinkling of stars is due to atmospheric
An optical fibre has a core material of refractive index of 1.55 and cladding material of refractive index of 1.50. The numerical aperture of the fibre is
- The refracting angle of a prism is $A$. The refractive index of the material of the prism is $\frac{1+\cos A}{\sin A}$. The angle of minimum deviation is:
