- #1

- 100

- 10

## Homework Statement:

- For electrical installations in homes and buildings, it is important to have control over electric and magnetic fields so that they do not disturb the environment in an undesirable way. Coaxial cables are very popular for transmitting information, they consist of an inner (circular) conductor with radius a and a thin outer conductor (shield) with radius b. Both conductors are separated by air. The inner conductor conducts a current whose current density decreases with distance, so that J(r) = k/r where k is a constant. The outer conductor conducts an equal current in the opposite direction. Determine the magnetic field inside and outside the cable.

## Relevant Equations:

- Amperes law, definition of current density.

My attempt:

I realized after i had tried to solve the problem that the current must be constant in the cables. But no information about where the cables has radius a and b is given so how would I go about to find an expression for the current?

Thanks in advance!

I realized after i had tried to solve the problem that the current must be constant in the cables. But no information about where the cables has radius a and b is given so how would I go about to find an expression for the current?

Thanks in advance!