At what rate do electrons flow through any cross section

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Homework Help Overview

The discussion revolves around calculating the rate of electron flow through a cross-section of a heater element, given a potential difference and power dissipation. The subject area includes concepts from electricity and circuits.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationship between current, charge, and the number of electrons flowing per unit time. There is an attempt to convert current into a rate of electron flow, with discussions on the units involved.

Discussion Status

Some participants have provided guidance on how to approach the calculation of electron flow, while others express uncertainty about the smallness of their results. Multiple interpretations of the problem are being explored, particularly regarding the conversion of current to electron flow.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may impose specific requirements for the format of the answer. There is also a noted confusion regarding the units and the expected form of the final answer.

mr_coffee
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I got the first part of this question but can't seem to get the 2nd part..
A 105 V potential difference is applied to a space heater that dissipates 1000 W during operation.

(a) What is its resistance during operation?
11.025 OHM
(b) At what rate do electrons flow through any cross section of the heater element?
wrong check mark s-1

Well that sounds like they want me to find the current, so i tried
[tex]P = i^2R[/tex]
[tex]i = sqrt((1000/11.025))[/tex];
i = 9.5238;
I submitted it konwing it would be wrong, because it said it wanted section s^-1. So i tried 1/i = .105, which is s, which was wrong, any ideas\? Thanks.
 
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Current is amount of charge flowing through an area per unit time. So this is rate of CHARGE FLOW, i.e. Q/time. Your question asked for rate of ELECTRON flow, which is number/time.

Since you already found Q/time, and you know how much charge each electron has, shouldn't it be rather straightforward to find out how many electrons actually flow across an area per unit time?

Zz.
 
OKay i think i got it, but the answer is so small I'm thinking its wrong how i did it...
If I'm trying to find what rate electrons flow thorugh any cross section of the heater element, I need to find # of electrons/time, like you said..
So:
#(1.68E-19)/seconds * (1 second/9.5238A) = 1.680E-20;
but that leaves me with CA, which isn't right...
I also tried 1.68E-19*9.5238
 
mr_coffee said:
OKay i think i got it, but the answer is so small I'm thinking its wrong how i did it...
If I'm trying to find what rate electrons flow thorugh any cross section of the heater element, I need to find # of electrons/time, like you said..
So:
#(1.68E-19)/seconds * (1 second/9.5238A) = 1.680E-20;
but that leaves me with CA, which isn't right...
I also tried 1.68E-19*9.5238

What did you do here?

You have current in x Amp., which is in units of coulombs/second. So

x C/s * 1e/1.6E-19C = #e/s

I believe this is a VERY large number.

Zz.
 

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