Ever wondered why a bird sitting on a power line doesn’t get electrocuted?

Ever wondered why a bird sitting on a power line doesn’t get electrocuted?

Here’s the answer...  
Electricity needs a path to flow — from a high voltage point to a low one.  
When a bird is touching just one wire, there’s no voltage difference across its body.  
No difference means no current, and no current means no shock.

But... if the bird touches another wire or a grounded object at the same time — zap.