Posted by **Selma** on Saturday, March 13, 2010 at 11:19pm.

A water pipe is made of iron with an outside diameter of 2.5 cm and inside diameter of 2.0 cm. The pipe is used to ground an electric appliance. If a current of 20 A flows from the appliance into the water pipe, what fraction of this current will flow in the iron? What fraction in the water? Assume that water has a resistivity of 0.010 Ω∙ m.

- Physics -
**drwls**, Sunday, March 14, 2010 at 8:27am
Compare the resistance of the annular pipe with that of the water column of the same length.

Riron = (r,iron)L/[pi(ro^2 - ri^2]

Rwater = (r,water)L/[pi*ri^2]

You will need to look up the resisitivity of iron pipe. It is about 10^-7 Ohm-meters, which is 10^-5 times that of water.

The area ratio

(ro^2 - ri^2/ri^2 = (ro/ri)^^2 -1 = 0.56

R,iron/R,water = 10^-5/0.56, so water will conduct only about 2* 10^-5 of the current

## Answer This Question

## Related Questions

- Physics - A horizontal water pipe goes from a large diameter to a small ...
- Geometry - The outside diameter of a pipe is 5 cm. The inside diameter is 4 cm...
- Math - A pipe has an outside diameter of 1.25 inches and an inside diameter of 0...
- algebra - A pipe manufacturer makes pipes of four different sizes. The diameter ...
- algebra - A pipe manufacturer makes pipes of four different sizes. The diameter ...
- physics - A thick, vertical iron pipe has an inner diameter of 0.070 m. A thin ...
- physics - What is the pressure change in water going from a 3.0- cm-diameter ...
- physics - A horizontal pipe 17.00 cm in diameter has a smooth reduction to a ...
- physics - A horizontal pipe 17.00 cm in diameter has a smooth reduction to a ...
- Physics - A horizontal pipe, 10 cm in diameter, has a smooth reduction to a pipe...

More Related Questions