MCQ Detailed View

When a bird perches on a high-tension electric wire, it does not get electrocuted because it does not form a closed circuit for the flow of current. Electricity always flows through a closed conducting path, moving from a region of higher potential (voltage) to a region of lower potential (usually the ground or another wire with different voltage).

In the case of a bird sitting with both feet on the same wire, both feet are at the same electric potential. Since there is no potential difference between the two points of contact, no current flows through the bird’s body. The absence of current prevents electrocution.

On the other hand, if the bird were to touch two wires of different potential at the same time (or a wire and the grounded pole), its body would become a path for current to flow. In that case, a large current could pass through its body, leading to electrocution.

This principle explains why electricians are trained never to touch two different high-voltage lines or a line and the ground simultaneously. The human body, like the bird, will only conduct electricity if a potential difference exists across it.

Key points to understand:

1. 
   

   Closed Circuit Requirement – Current flows only in a closed loop. The bird on one wire does not complete a circuit.

   
   


2. 
   

   Same Potential Contact – Both feet of the bird rest on the same conductor, hence no potential difference.

   
   


3. 
   

   Risk of Electrocution – If the bird touches another wire or the ground, it forms a circuit, allowing current to flow.

   
   


4. 
   

   Practical Example – Linemen working on high-voltage lines use special insulation equipment to prevent current flow through their bodies.

   
   

Thus, the bird remains unharmed because it is not providing a conductive path for the electricity to flow into the ground or across wires of different voltages.