Physics education research, electronic materials, and the musings of Christopher Moore, Ph.D.

tamara wrote:

I understand (or at least I think I understand) that birds do not get electricuted when they land on power lines because there is no difference in electric potential since they are only touching the wire and not anything else--were they to reach out and place another foot on another wire they'd be zapped....

Yes...assuming that the other wire were at a significantly different potential (i.e., such that the potential difference between the two wires was sufficiently large to cause a lethal current to flow through the poor bird). For power lines, that's a good assumption.

tamara wrote:

but....I'm confused at why you don't get electricuted when you grab two wires to electrical appliances in your home at the same time and what not.

Just like the bird, you would be electrocuted if the two wires were at significantly different potentials. (And such home-appliance electrocutions do indeed occur.)

tamara wrote:

I guess I just don't understand power lines---
are they not covered in a protective coating of rubber (or whatever it is) like the wires to the appliances in our homes are?

Power lines typically are not insulated.

tamara wrote:

What about phone lines and cable lines---can they cause electric shock?

They are low-voltage transmission facilities...not enough potential difference between their wires to electrocute you.