Question

Birds puff up their feathers in winter
A. So that they can trap more air
B. So that can develop charge
C. Can't say
D. So that friction reduces

Answer 1

Hint: Winter is a cold season. Birds have big feathers. They puff up their feathers like a sweater to keep themselves warm. Whereas to develop charge they must be rubbed against another charged material.

Complete solution Step-by-Step: Birds often puff or open and close their wings often during the winters. When birds puff up their feathers, they trap air in between them. . We also know that air is a bad conductor or good insulator of heat, it prevents the heat from the body of the bird from escaping or flowing out of their bodies. Thus keeping them warm even during harsh climates.

Also, bigger the feathers, more the air trapped , more the insulation and hence more the warmth felt. Small birds, with small feathers, puff more often as compared to big birds with bigger feathers. Birds' feathers are designed to keep them warm and waterproof during the winters. The feathers are coated with an oil like substance which acts as a waterproof material, preventing the birds from getting wet and cold.

Hence, A. Birds puff up their feathers in winter so that they can trap more air, is the answer.

Additional Information: Birds feathers are designed to keep them warm and waterproof during the winters. The feathers trap air to keep them warm. Small birds, with small feathers, puff more often as compared to big birds with bigger feathers.

Note: Air is a bad conductor or good insulator of heat, it prevents the heat from the body of the bird from escaping. Bigger the feather the more the insulation and hence the more the warmth. Whereas to develop charge they must be rubbed against another charged material. Similarly there is no friction here, to reduce.