Calculating Current in a Wire of Given Dimensions

AI Thread Summary
A wire with a radius of 1.2mm carrying a current of 3.2A has a calculated electron drift velocity of approximately 0.177 m/s, based on the provided electron density of 2.5x10^25 electrons per cubic meter. However, this electron concentration is considered low for a metal wire, which typically ranges from 10^28 to 10^29 electrons per cubic meter. A correction was noted regarding the cross-sectional area calculation, which should be 4.5x10^-6 m² instead of 4.5x10^6 m², but this typo does not impact the final drift velocity result. The discussion also raised a question about how doubling the wire's cross-sectional area would affect the drift velocity. Overall, the calculations and assumptions about electron density in the wire material are crucial for accurate current and drift velocity assessments.
Johnahh
Messages
88
Reaction score
0

Homework Statement


a wire carrying a current of 3.2A has a radius of 1.2mm. the material of the wire has 2.5x10^25 free electrons per cubic metre. the elementary charge is 1.6x10^-19


Homework Equations


I=Anev
cross section = pi*r^2



The Attempt at a Solution


pi*0.0012^2 = 4.5x10^6

3.2/4.5x10^6*2.5x10^25*1.16x10^-19 = 0.1777 recurring
I am sure this is not correct as it seems to fast, I have seen some examples and they are more like 2.8x10^-4 m/s
Am i supposed to make 2.5x10^25 into 2.5x10^19 for mm^3 instead of m^3?
Any help please?
 
Physics news on Phys.org
2.5 x10^25 electrons per cubic metre is very low value for a metal wire. It should be in the range 10^28-10^29 electron/m^3.

ehild
 
you have the cross sec area as 4.5x10^6 ...it should be 4.5x10^-6... this is just a typing error and does not affect your answer.
For the figures you have given I also get 0.177
I agree with ehild regarding electron concentration for a metal. 10^28 to 10^29
 
Yeah it was a typo sorry. OK so the electron drift is 0.177 m/s. What happens if the cross section doubles in size is it v*2 or v/2? Thanks
 
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »

Similar threads

Flux between two current-carrying wires
Replies
8
Views
3K
How to Calculate the Current Flowing Through a Gold Wire?
Replies
8
Views
2K
What is the current in the wire?
Replies
4
Views
26K
Calculating current given the current density and area
Replies
2
Views
2K
Resistance, current and current density
Replies
8
Views
2K
Calculating Current in a Wire with a Moving Charged Particle
Replies
3
Views
2K
Calculate the required current flow in the suspended wire
Replies
7
Views
5K
Calculating Current in a Suspended Copper Wire System
Replies
9
Views
4K
How to calculate wire extension from tension and Young's modulus?
Replies
1
Views
3K
Find Electron Current Through Iron Wire
Replies
1
Views
11K

Hot Threads

Recent Insights

Back
Top