Resistivity and Ohm's Law question

  • #1

Homework Statement


A long wire connected to the terminals of a 12V battery has 6.4 x 1019 electrons passing a cross section of wire each second. calculate it's resistance.

answer is 1.2Ω


Homework Equations


q = ne
q = IE
R=ρ L/A


The Attempt at a Solution


V= 12v
n= 6.4 x 1019 electrons
R=?

First I used the number of electrons to find my charge (q)
q = ne
q = (6.4 x 1019) ( 9 x 10-31)
q = 5.76 x 10 -11

Then calculating my current
I= Q/T
Im assuming T is 1s, because it says "passing a cross section of wire each second"
I = 5.76 x 10 -11/ 1
I= 5.76 x 10 -11

Then i calculated my resistance
R= V/R
R= 12/5.76 x 10 -11
R= 2.0 x 1011

What am i doing wrong? D:
 

Answers and Replies

  • #2
rock.freak667
Homework Helper
6,230
31
The charge of an electron is e=1.6(10-19) C.
 
  • #3
Simon Bridge
Science Advisor
Homework Helper
17,857
1,655
q = ne
q = (6.4 x 1019) ( 9 x 10-31)
... that would be the electron mass.

e=1.60217646×10-19 Coulombs
 
  • #4
The charge of an electron is e=1.6(10-19) C.
... that would be the electron mass.

e=1.60217646×10-19 Coulombs
LOL! CRAP! i knew that~ :) Thank you :3 I was going insane for a bit.
 
  • #5
Simon Bridge
Science Advisor
Homework Helper
17,857
1,655
Happens to the best of us :-)
 

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