Q. 64

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Found in: Page 904

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

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

# Consider current passing through a resistor of radius , length , and resistance .a. Determine the electric and magnetic fields at the surface of the resistor. Assume that the electric field is uniform throughout, including at the surface.b. Determine the strength and direction of the Poynting vector at the surface of the resistor.c. Show that the flux of the Poynting vector (i.e., the integral of ) over the surface of the resistor is . Then give an interpretation of this result.

a) The electric and magnetic fields at the surface of the resistor,

b) The strength and direction of the Poynting vector at the surface of the resistor,

c)The flux of the Poynting vector over the surface of the resistor,

See the step by step solution

## Step 1: Calculate the fields which is on the surface of resistor. (part a)

a.

The charge changes with respect to time is,

Charge enclosed is,

By above equation,

## Step 2: find Poynting vector's strengths and directions (part b)

b)

Using ohms law,

Poynting vector shown as,

By above equation, you got

## Step 3: The flux of Poynting vector (part c)

c)

Multiplication of electric field and magnetic field of resistors gives flux of the poynting vector,