Explanation Given info: The applied potential difference is 12 V , length of the wire is 6.9 m , the diameter of the wire is 0.33 mm and the electric current in the wire is 2.1 A . Formula to calculate the resistance of a wire is, R = ρ L A (1) Here, L is the length of the wire. A is are of cross-section of wire. ρ is the resistivity of the wire material. The expression for cross-section of the wire is, A = π d 2 4 Here, d is the diameter of the wire. Substitute π d 2 4 for A in equation (1). R = ρ L π d 2 4 (2) The ohm’s law is, V = I R R = V I (3) Here, V is the voltage. I is the current. R is the resistance. Substitute V I for R in equation (2) to eliminate R from the equation. V I = ρ L π d 2 4 ρ = V π d 2 4 I L Substitute 12 V for V , 6

5th Edition

ISBN: 9780321976444

Author: James S. Walker

Publisher: PEARSON

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Resistivity

Resistivity is a characteristic property of the conductor’s material that measures the extent to which the material opposes the flow of current. It is denoted by the Greek letter “rho”. Electrical resistivity, also known as specific resistance, depends o…

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Chapter 21, Problem 18PCE

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The resistivity of the wire.

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The resistivity of the wire.

Solution Summary: The author explains the formula to calculate the resistance of a wire: R=rho LA

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