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Chapter 27: Q. 5 (page 761)

What is the difference between current and current density?

Short Answer

Expert verified

Charge moves through a wire at a rate known as current.

The density of current flow within the conductors is called current densityJ=IA.

Step by step solution

01

Concept Introduction

A conductor's current is defined as the rate at which electric charges flow through it. Current density is defined as the volumetric flow of charge per unit area through a conductor.

02

Explanation (Part a)

Difference between current and current density:

The current flow is sustained by an established electric field.

I=qt

Here, Iis current in Ampere, qis charge in Coulomb, and tis time in seconds.

The current density written as follows.

J=IA

Here, Jis current density in A/m2,Iis current in Amperes, and Ais area of conductor in m2.

03

Final Answer

Hence, In conductors, the current density can be defined as the density of current flow within the conductors. A stable current means that its magnitude and direction will always remain the same.

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Most popular questions from this chapter

72. You've decided to protect your house by placing a 5.0-m-tall iron lightning rod next to the house. The top is sharpened to a point and the bottom is in good contact with the ground. From your research, you've learned that lightning bolts can carry up to 50kAof current and last up to 50μs.

a. How much charge is delivered by a lightning bolt with these parameters?
b. You don't want the potential difference between the top and bottom of the lightning rod to exceed 100V. What minimum diameter must the rod have?.

II You need to design a 1.0Afuse that "blows" if the current exceeds 1.0A. The fuse material in your stockroom melts at a current density of 500A/cm2. What diameter wire of this material will do the job?

For what electric field strength would the current in a 2.0mmdiameter nichrome wire be the same as the current in a 1.0mmdiameter aluminum wire in which the electric field strength is0.0080V/m?

21. A 0.0075V/m electric field creates a 3.9mA current in a 1.0-mm-diameter wire. What material is the wire made of?

A 1.5m long wire is made of a metal with the same electron density as copper. The wire is connected across the terminals of a 9.0V battery. What conductivity would the metal need for the drift velocity of electrons in the wire to be 60mph? By what factor is this larger than the conductivity of copper?
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