Question

Between the primary and secondary rainbows, there is a dark band known as Alexandar’s dark band. This is because ______.

1. light scattered into this region interfere destructively.
2. there is no light scattered into this region.
3. light is absorbed in this region.
4. angle made at the eye by the scattered rays with respect to the incident light of the sun lies between approximately 42° and 50°.

Options

• a and c

• a and d

• b and d

• c and d

Answer 1

a and d

Explanation:

The Alexandar’s dark band lies between the primary and secondary rainbows, formed due to light scattered into this region interfere destructively. The primary rainbows subtend an angle of nearly 41° to 42° at the observer’s eye, whereas secondary rainbows subtend an angle of nearly 51° to 54° at the observer’s eye w.r.t. incident light ray.

Hence, the scattered rays with respect to the incident light of the sun lie between approximately 42° and 50°.