Animals and Current Electricity

[Soaring Crane]

I was glancing at a physics book, and two questions in the electricity section caught my eye.

Why does a cow that touches an electric fence experience a mild shock?

Why can birds perch on high-voltage lines without being injured?

For the second one, I believe it is that their "feet" are better insulated. (Don't some die, however?) What about the first one?

Thanks.

 

[Blistering Peanut]

The one about the bird...

It can perch on one wire without being electrocuted as there is no reason why the electricity should flow through the bird. If the bird was touching the ground as well as the wire current would flow through the bird to be earthed in the ground. Standing on a single wire does not let this happen.

The same reason goes for the cow, current flows through his skin and down through his leg into the Earth and this stimulates the pain receptors and the muscles which give it a shock.

Interestingly I was reading that AC current supplied to our houses has a frequency of 50Hz for the opposite reason to the cow one. Apparently our muscles respond (would resonate be the right word here?) worst to this frequency so we experience a lot less pain and we should be able to release a grip from whatever was giving us the shock.

Please correct me if I'm wrong I haven't quite got onto university physics yet.

 

[Graeme Robinson]

The reason a cow experiences a mild shock when touching an electric fence is because the cow's body is a conductor of electricity. When the cow touches the fence, it creates a complete circuit, allowing the electricity to flow through the cow's body and back into the ground. This flow of electricity can cause a mild shock sensation.

As for birds perching on high-voltage lines, they are able to do so without being injured because birds have a very high resistance to electricity. This means that they are not good conductors of electricity, so the current does not flow through their bodies. Additionally, birds have an adaptation called the Hall effect, which allows them to sense and avoid high-voltage areas.

While some birds may die from electrocution on high-voltage lines, it is usually due to their wingspan or other body parts coming into contact with multiple lines at once, creating a strong enough current to cause harm. Overall, birds are able to safely perch on high-voltage lines due to their natural resistance to electricity and their ability to sense and avoid dangerous areas.