Capacitance of a cylindrical capacitor

AI Thread Summary
The discussion focuses on calculating the capacitance per meter of a coaxial cable with specified inner and outer radii, filled with polystyrene. The formula used for the calculation is C = (2 * π * E * K) / ln(b/a), where K is the dielectric constant. An initial attempt yielded a result of 551.05 pF/m, which was incorrect. After further review, the correct capacitance was determined to be 98.596 pF/m, highlighting the importance of careful calculations. The thread emphasizes the need for accuracy in using formulas and calculators in physics problems.
stosw
Messages
19
Reaction score
0

Homework Statement



A coaxial cable used in a transmission line has an inner radius of 0.15 mm and an outer radius of 0.65 mm. Calculate the capacitance per meter for the cable. Assume that the space between the conductors is filled with polystyrene. (Also assume that the outer conductor is infinitesimally thin).


Homework Equations



C=\frac{2*pi*E*K}{ln(b/a)}

The Attempt at a Solution



After converting mm to m and plugging in values (used K = 2.6 for capacitance per meter) I got 551.05 pF/m.

Webassign has told me this is incorrect. Could someone point me where I went wrong?
 
Physics news on Phys.org
I get a completely different answer when I plug the numbers in. Try showing your work here so we can see where your error is.
 
Thanks.
Guess I should be more careful when using a calculator.

Correct answer is 98.596 pF/m
 
Thread 'Voltmeter readings for this circuit with switches'

Thread 'Voltmeter readings for this circuit with switches'

TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
View full post »
Thread 'Correct statement about a reservoir with an outlet pipe'

Thread 'Correct statement about a reservoir with an outlet pipe'

The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...
View full post »

Similar threads

Why Capacitors in Parallels vs. Series: Coaxial Capacitor Case
Replies
2
Views
2K
Shell in a cylindrical capacitor
Replies
1
Views
2K
Capacitance of Coaxial Cable Configuration with Multiple Conductors
Replies
1
Views
4K
How Do You Calculate the Capacitance of a Coaxial Cable with Polystyrene?
Replies
1
Views
3K
Average Energy Density of Capacitor
Replies
2
Views
4K
Find the electric field between 2 finite discs
Replies
16
Views
1K
Power Transmitted in a Coaxial Cable
Replies
7
Views
4K
Resistance, current and current density
Replies
8
Views
2K
What is the electric field inside a coaxial cable with given charge densities?
Replies
7
Views
7K
Derivation of capacitance for two shells
Replies
4
Views
1K

Hot Threads

Recent Insights

Back
Top