At what rate do electrons flow through any cross section

In summary, the question asks for the resistance and rate of electron flow in a space heater with a 105 V potential difference and 1000 W power output. The resistance is found to be 11.025 ohms, and to find the rate of electron flow, the number of electrons flowing through an area per unit time must be calculated. This is done by taking the current in amps and converting it to coulombs per second, and then dividing it by the charge of an electron. The resulting number is a large value.
  • #1
mr_coffee
1,629
1
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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  • #2
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.
 
  • #3
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
 
  • #4
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.
 

FAQ: At what rate do electrons flow through any cross section

How is the rate of electron flow through a cross section measured?

The rate of electron flow through a cross section is measured by determining the amount of charge passing through the cross section per unit time, also known as current.

What factors affect the rate of electron flow through a cross section?

The rate of electron flow through a cross section can be affected by the material of the conductor, temperature, and the presence of any external electric or magnetic fields.

Is the rate of electron flow through a cross section constant?

No, the rate of electron flow through a cross section can vary depending on the conditions mentioned above. It can also be controlled by devices such as resistors or switches.

How is the rate of electron flow through a cross section related to voltage?

The rate of electron flow through a cross section is directly proportional to the voltage applied across that cross section. This relationship is described by Ohm's law: I = V/R, where I is the current, V is the voltage, and R is the resistance of the material.

Can the rate of electron flow through a cross section be increased?

Yes, the rate of electron flow through a cross section can be increased by increasing the applied voltage, decreasing the resistance of the material, or by increasing the cross-sectional area of the conductor.

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