Between the primary and secondary rainbows, there is a dark band known as Alexandar's dark band. This is because:
(a) light scattered into this region interfere destructively
(b) there is no light scattered into this region
(c) light is absorbed in this region
(d) angle made at the eye by the scattered rays with respect to the incident light of the sun lies between approximately 42 and 50
1. (a, c)
2. (a, d)
3. (b, d)
4. (c, d)
(2) Hint: Use the concept of the formation of the rainbow.
Step 1: Interpret the reason for the formation of Alexandar's dark band.
Alexandar's dark band lies between the primary and secondary rainbows, forms due to light scattered into this region interfere destructively.
Step 2: Find the angle subtended by the rays in this region.
Since primary rainbow subtends an angle nearly 41 to 42 at the observer's eye, whereas, secondary rainbows subtends an angle nearly 51 to 54 at the observer's eye w.r.t. incident light ray.
So, the scattered rays with respect to the incident light of the sun lies between approximately 42 and 50
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