a 20cm long hollow nichrome tube of inner diameter 2.8mm, outer diameter 3.0mm is connected to a 3.0V battery. What is the current in the tube?(adsbygoogle = window.adsbygoogle || []).push({});

I think this is a I = V/R problem. So i used R=([tex]\rho[/tex]*L)/A. Where L is the length of the wire and A is the outer area minus the inner area and rho is the resistivity of nichrome.

A =.003^2*[tex]\pi[/tex] - .0028^2*[tex]\pi[/tex] = 3.64*10^-6

R = ((1.5*10^-6) * (.02))/3.64*10^-6 = .0823

I = 3/.0823 = 36.44Amps

However the answer is 9.1A apparently. Where have i gone wrong?

Thanks!!

btw if the greek symbols appear superscript they are not supposed to be I cant quite figure that part out

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Current/Voltage/Resistance HELP!

**Physics Forums | Science Articles, Homework Help, Discussion**