Why don't bird get shock on power lines?

Birds don’t get electrocuted when they sit on a single power line because electricity flows through a path with a voltage difference. Since both of the bird’s feet are on the same wire at the same voltage, there's no potential difference — and therefore, no current flows through the bird's body.

Detailed Explanation:

1. Electricity Needs a Path (Potential Difference):

Electric current flows from a point of higher electric potential (voltage) to a point of lower potential — but only when there's a closed path. For current to pass through a bird’s body, there would need to be a voltage difference between two points it touches. When a bird perches on a single wire, both of its feet are at exactly the same voltage, so no current flows through its body.

2. Conductivity and the Bird’s Body:

Electricity takes the path of least resistance. Copper or aluminum wires are much better conductors than a bird's body. Even if there were a very tiny potential difference (like due to induced voltage or a slight imbalance), the current would still prefer to travel through the wire rather than the bird’s relatively resistive body. The bird essentially becomes invisible to the current.

3. Why Birds Can Get Shocked:

If a bird touches two wires at once (like one foot on each wire of different voltage, or one foot on a wire and the other touching a grounded object like a pole), there will be a voltage difference across its body. In that case, current would flow, and the bird could get shocked or killed. This is why birds avoid large gaps or high-voltage connections — they're instinctively cautious.

4. Human Danger is Different:

When a person touches a high-voltage wire while standing on the ground, there's a large voltage difference between the wire and the ground (zero volts), causing current to flow through the person’s body to the earth — leading to electrocution. That’s why humans need insulated tools, protective gear, or must be completely isolated to safely work on power lines (as linemen sometimes do with helicopters).

Summary:

Birds don't get shocked on power lines because they only touch one wire, so there's no voltage difference across their body — no current flows, so they’re safe. But if they touch two different voltages (like two wires or a wire and a pole), they can be electrocuted. It's all about electric current needing a complete path and a voltage difference to flow.