• Support PF! Buy your school textbooks, materials and every day products Here!

Find current drawn from the cell

  • #1
utkarshakash
Gold Member
855
13

Homework Statement


A cylindrical conductor of length l and inner radius R1 and outer radius R2 has specific resistance ρ A cell of emf e is connected across the two lateral faces of the conductor. Find the current drawn from the cell.


The Attempt at a Solution


Consider a thin shell of radius dx from the centre of the cylinder.

[itex]dR = \dfrac{\rho l}{2\pi x dx} \\

di=\frac{e}{dR} [/itex]

Now, if I integrate the above equation I get a different answer.

Homework Statement





Homework Equations





The Attempt at a Solution

 

Attachments

Answers and Replies

  • #2
tms
644
17
Why are you integrating? You can find the cross-sectional area of the cylinder directly.
 
  • #3
3,732
414
It's not very clear but I think the connections are applied to the cylindrical surfaces and not to the flat surfaces at the end. So the current will be radial rather than axial. Usually the "lateral area" of a cylinder is used to designate the area of the curved surface not of the flat bases.

If this is NOT the case, then it is a trivial problem and you don't need to integrate.

And what do you mean by a "different answer"? Different in respect to what?
 
  • #4
tms
644
17
It's not very clear but I think the connections are applied to the cylindrical surfaces and not to the flat surfaces at the end. So the current will be radial rather than axial. Usually the "lateral area" of a cylinder is used to designate the area of the curved surface not of the flat bases.
I do believe you are correct.

In that case, when setting up the integral, the OP should be careful about what is the length and what is the area (with respect to the resistivity) when setting up the integral. The equation he used is not correct.
 

Related Threads for: Find current drawn from the cell

Replies
5
Views
3K
Replies
3
Views
1K
Replies
1
Views
13K
Replies
4
Views
7K
Replies
3
Views
448
  • Last Post
Replies
4
Views
555
Replies
2
Views
3K
Replies
4
Views
1K
Top