Resistivity and Ohm's Law question

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Homework Help Overview

The problem involves calculating the resistance of a long wire connected to a 12V battery, given the number of electrons passing through a cross-section of the wire per second. The subject area pertains to resistivity and Ohm's Law.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to calculate resistance using the number of electrons to find charge, then determining current and finally resistance. Some participants question the use of the electron mass instead of charge in the calculations.

Discussion Status

The discussion is ongoing, with participants providing clarifications about the charge of an electron and correcting the original poster's approach regarding the use of mass versus charge. There is a light-hearted acknowledgment of the confusion experienced by the original poster.

Contextual Notes

Participants note the correct value of the charge of an electron, which is crucial for the calculations, and highlight the potential misunderstanding in the original poster's use of variables.

Vickyvicksss
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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:
 
Physics news on Phys.org
The charge of an electron is e=1.6(10-19) C.
 
q = ne
q = (6.4 x 1019) ( 9 x 10-31[/color])
... that would be the electron mass.

e=1.60217646×10-19 Coulombs
 
rock.freak667 said:
The charge of an electron is e=1.6(10-19) C.

Simon Bridge said:
... 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.
 
Happens to the best of us :-)
 

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