Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
0 votes

What is the capacitance of a 1 m long hifi cable where the central conductor is 1 mm in diameter and the shield is 5 mm in diameter?

Can you answer this question?

1 Answer

0 votes
Here $C=?,L=1m$
$r_a=\large\frac{1}{2}$$ mm=0.5 mm= 5 \times 10^{-4} m$
$r_b=\large\frac{5}{2}$$ mm=2.5 mm=2.5 \times 10^{-3} m$
For a cylindrical capacitor.
$C= \large\frac{2 \pi \in_0 L}{\log_e \bigg( \Large\frac{r_a}{r_b} \bigg) }$
$\quad= \large\frac{4 \pi \in_0 L}{2 \log _e (r_a/r_b)}$
$\quad= \large\frac{1 \times 1}{9 \times 10^3 \times 2 \log_e \bigg( \Large\frac{2.5 \times 10^{-3}}{5 \times 10^{-4}} \bigg)}$
$\quad= 3.45 \times 10^{-11}F$
$\quad= 34.5 \times 10^{-12} F= 34.5 pF$
Hence B is the correct answer.
answered Jun 13, 2014 by meena.p

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, AIPMT Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App