Why can a bird land on a power line without being shocked?

The reason a bird can land on a power line without being shocked is because it is not grounded. When a bird perches on a power line, it is not providing a path for electricity to flow to the ground. Electrical current requires a complete circuit to flow, which means it needs a source of high voltage and a return path to a lower voltage (ground). Since the bird is sitting only on the power line, and is not touching any other conductive material or the ground, there is no potential difference between its feet. Without that potential difference, the electrical current does not flow through the bird, thus avoiding any shock.

The other options suggest protective measures or characteristics that do not accurately describe the physics involved. For example, birds do not require insulating shoes because the situation of electricity flow relies on how electrical circuits work rather than the materials used on their feet. Similarly, feathers do not repel electricity; rather, it’s the lack of a pathway for current that keeps them safe. Lastly, power lines are continuously energized; birds can land on them anytime as long as they maintain that non-grounded state. Thus, the fundamental concept that the bird is not grounded is pivotal to their safety when perching on power lines.