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Q. 56

Expert-verified
Found in: Page 833

### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

Book edition 4th
Author(s) Randall D. Knight
Pages 1240 pages
ISBN 9780133942651

# The coaxial cable shown in consists of a solid inner conductor of radius surrounded by a hollow, very thin outer conductor of radius . The two carry equal currents I, but in opposite directions. The current density is uniformly distributed over each conductor.a. Find expressions for three magnetic fields: within the inner conductor, in the space between the conductors, and outside the outer conductor.

The magnetic field increase till reaching the surface of the inner wire then it decreases as increases till reach after this point it becomes Zero

See the step by step solution

## Step 1 : Given Information

Finding the expressions for three magnetic fields.

## Step 2 : Calculation

To get the magnetic field of Ampere's law need to integrate over the circumference of the enclosed area.

The current density inside the enclosed area (r) equals the current density in the whole wire of radius

is the current of wire.

The current

Need to get B with the expression of I into equation (1).

The magnetic field is inside the wire when

The distance and the current is the same for the wire with the radius

## Step 3 : Explanation.

The distance and the current is the same for the wire with the radius

The current flows at Distance the net current in the path is zero. From Ampere's law the magnetic field will be zero

## Step 4 : Simplification.

In the magnetic field the surface of the inner wire decreases as r increases till reach, after this point it becomes zero.