Final answer:
Birds don't get electrocuted on power lines because there's no voltage difference across their body while perched on a single wire. However, if they bridge two wires with different voltages, it creates a circuit, and they can be electrocuted. Studies have shown no consistent health risks from living near high-voltage power lines.
Step-by-step explanation:
Why Birds Don't Get Electrocuted on Power Lines
A bird can perch on a high-voltage power line without getting a shock because there is no voltage difference across its body. Current flows when there is a circuit or path created with a potential difference. Since the bird's feet are close to each other on the same wire, and they are not touching the ground or another wire with a different voltage, there is no significant current flow through the bird's body.
Contrast this with a situation in which a large bird's wings touch two different wires at the same time. In this scenario, the bird would complete a circuit between wires with different voltages, which can lead to a current flowing through the bird's body, resulting in electrocution.
Misconception Alert: Despite beliefs to the contrary, high-voltage power lines have not been conclusively linked to health issues such as cancer, according to studies and reports by the American Physical Society.