# Current in a silver-lined tube

1. Sep 7, 2008

### Feldoh

1. The problem statement, all variables and given/known data
A plastic tube 25m long and 4cm in diameter is dipped into a silver solution, resulting in a layer of silver being deposited 0.1mm think uniformly over the outer surface of the plastic tube. The coated tube is then connected across a 12V battery. Calculate the current.

2. Relevant equations
Current/Resistance equations that are time invariant

3. The attempt at a solution
I THINK that I need to find the current density in order to solve this problem, however I cannot think of a way to find it. I also thought about some way to do this by finding the resistance but you need the resistivity of silver. I could look on line but the value isn't provided in my book or in the homework set so I thinking that I'm not supposed to just look-up the resistivity of silver.

2. Sep 7, 2008

### Staff: Mentor

I would just look up the resistivity of silver, calculate the resistance of that geometry, and use that to calculate the current. Don't worry that the book doesn't give you the rho of silver -- it's common to look up resistivities of materials in a CRC handbook or nowadays just online.