Question

Consider a coaxial cable with inner radius of 1 mm and outer radius of 3 mm. The region in between inner surface and outer surface is filled with dielectric material ${\mu }_1=1,{\epsilon }_r=1$ and has zero initial inductance. The inductance for a coaxial cable of length 1 km is _______$\mu H$.

• A. 219.72

Answer 1

The correct option is A 219.72
219.72

$\frac{L}{l}=\frac{\mu }{2\pi }ln\left(\frac{a}{b}\right)$

= $\frac{4\pi \times {10}^{-7}}{2\pi }ln\frac{3}{1}$
$\frac{L}{l}=0.21972\mu H/m$

Inductance for 1 km ,
L = 0.21972 $\times$ 1000

=219.72 $\mu H$