Bird on electric wire: theoretical distance between the two bird legs

Question

Hey guys, please someone help me with this exercise :)

For our exercise, assume that the bird’s body resistance (from leg to leg) is 50kΩ. Given is a high voltage power line with a current of 100A where the bird takes a rest. The high voltage power line is made out of aluminium, which has a conductivity of $3.79\times10^7 \,\rm S/m$ and a cross section of $100\rm\, mm^2$. 
Determine the theoretical distance between the two bird legs.

I know, the formula is V = R x I

I = 100 A, right?

R = ?

Please someone explain step by step?

Thanks.

Answer 1

The way you have asked the question there is not enough information...

To work out R of the wire you have the conductivity and cross section of the wire..., but you also need the length of wire, which might be the unknown (the gap between the birds legs).

If you have the voltage between the two legs you can go forward with this by working out the resistance of the wire, R, and then you can use conductivity and cross section to work out your length....- is the voltage between the legs in your question?

Answer 2

I think you might be missing information, as tom pointed out. For example you can look at this setup as a resistor (the bird) in parallel with the power line. You do need to specify something more about the bird, perhaps the power transferred...

Answer 3

Have a look at Birds sitting on electric wires: potential difference between the legs this gives some very good answers, which suggest any pd across and current through is entirely negligible (assuming a standard bird as defined by European law). Essentially, the pd drop over significant distances is small by design so that it is correspondingly smaller over smaller distance.