Question

IP A bird lands on a bare copper wire carrying a current of 36 A A . The wire is 8 gauge, which means that its cross-sectional area is 0.13 cm 2  cm2 .

Find the difference in potential between the bird's feet, assuming they are separated by a distance of 4.0 cm cm .

Will your answer to part A increase or decrease if the separation between the bird's feet increases? Explain

Answer 1

When the bird sits on the wire, the bird's feet are at the same potential and hence there won't be any potential difference. i.e, the potential difference is zero.

Even if the separation between bird's feet increase, the potential difference will be zero as the bird's feet are at the same potential.

But if you want to calculate the negligible potential difference due to the resistance of the wire, we can use the formula,

Potential Difference = (Current x Resistivity of the wire x Distance between birds feet ) / Cross sectional Area of wire

Hence,

Potential difference = 36 x 1.68*10^-8 x 4*10^-2 / 0.13*10^-4 = 0.00186 V

If the distance between the birds feet increases then this potential difference increases.