A bird perches on a bare high power line. What happens to the bird?

The correct answer is Option (3) → It is practically not affected.

A current flows through a body only when there is a potential difference across it. Both feet of the bird rest on the same wire, so they are at practically the same potential.

Option (1) It gets killed instantly. — Incorrect. A fatal shock needs a large current through the body, driven by a large potential difference. This happens to a man on the ground who touches the line. The bird does not touch any point at a different potential.

Option (2) It gets a mild shock. — Incorrect. Even a small current needs a potential difference between the two points of contact. The two feet on the same wire have none to drive it.

Option (3) It is practically not affected. — Correct. With no potential difference between its feet, no current passes through the bird, however high the potential of the line itself.

NCERT (2026-27):
Example 2.7 – “… and nothing happens to the bird. A man standing on the ground touches the same line and gets a fatal shock. Why? … (d) Current passes only when there is difference in potential.”