Between the primary and secondary rainbows, there is a dark band known as Alexander's dark band. This is because

Options

A. light scattered into this region interferes destructively.
B. there is no light scattered into this region.
C. light is obsorbed 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^(@)`.

Answer

A, D

Explanation

Alexander's dark band between the primary and secondary rainbows is because light scattered into this region interferes destructively. Further, primary rainbow subtends an angle of `41^(@) -43^(@)` at the eye of the observer w.r.t. the incident light, and secondary rainbow subtends an angle of about `51^(@)` to `54^(@)` at the eye of the observer w.r.t. the incident light. Therefore, the region between the angles of `41^(@)` to `51^(@)` us dark.
The choices (a) and (d) are correct.