You often see small birds perched on power lines, mistaking them for ordinary tree branches. They frequently gather in flocks on these lines, especially on medium and high-voltage power lines, yet they are not electrocuted.
Why is this the case, while we would get shocked, or even face fatal consequences, if we accidentally touched exposed wires? Is it because birds wear insulating shoes that prevent them from being shocked while perching on power lines? Not quite.
Electric current is the movement of electrons through a conductor. It always follows the path of least resistance, meaning it seeks out the route with the least electrical resistance to flow through.
The difference in resistance is the main reason birds are not shocked when perched on power lines.
Power lines are typically made of copper, which has the lowest resistivity and is an excellent conductor of electricity.
In contrast, the body of a bird has a higher resistivity and is a much poorer conductor than copper. As a result, the electric current bypasses the bird’s body and flows through the power line instead. Consequently, the bird does not get electrocuted.
Moreover, electricity flows from areas of higher voltage to areas of lower voltage. The power lines often have different voltage levels. If both of a bird’s feet are on the same wire, they are at the same voltage. Therefore, the bird remains unharmed.
However, if a bird stands on two different wires (with different voltage levels), the current will flow through its body from the wire with the higher voltage to the wire with the lower voltage, resulting in an electric shock.
On the other hand, when we stand on the ground, our body touches the live wire, creating a circuit. The current then flows from our body to the ground, causing an electric shock.
If we wear rubber-soled shoes, which have good insulating properties, or stand on an insulated wooden chair, we can touch the live wire without getting shocked. In this state, we resemble the bird perched on the power line. Some professional electricians who understand this principle can work safely while handling live wires.
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