# Voltage experience by the bird

1. Sep 30, 2009

### Liketothink

1. The problem statement, all variables and given/known data
A bird stands on an electric transmission line carrying 2210 A, as seen in the figure below. The line has 3.32E-5 Ω resistance per meter and the bird's feet are 3.80 cm apart. What voltage does the bird feel?

2. Relevant equations

R=sigma(L)/A
I=V/R

3. The attempt at a solution
I wanted to solve for V of the bird, but neither the resistance of the bird nor the area of the bird is given. Help?

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2. Sep 30, 2009

### mgb_phys

You are trying to find the voltage difference between the two points on the wire.
Think of the section of wire as a resistor

3. Sep 30, 2009

### Integral

Staff Emeritus
You are asked to find the potential difference between the birds legs. You do not need to know anything about the bird to find this. Your are given a resistivity, a distance and a current. Find the voltage.

4. Sep 30, 2009

### turbo

I think you are being asked to calculate the difference in potential (voltage) between the bird's feet. Just leave the bird out of it and calculate the voltage drop over 3.8 cm of transmission line.

Edit: Oops! Upstaged TWICE

5. Sep 30, 2009

### Liketothink

Ok so I got it by using voltage loss=amps*wire resitance/meter*distance
Usually this equation is
voltage loss=amps*wire resitance/meter*distance*2 wires
Why was it not necessary to multiply the answer by 2 in this case?

6. Sep 30, 2009

### mgb_phys

Where did the 2 come from ?

7. Sep 30, 2009

### Liketothink

I thought that was the equation for voltage loss. Is it not?

8. Sep 30, 2009

### turbo

Is the "2" perhaps included in that to calculate the voltage loss over a 2-conductor cable, like a lamp-cord?