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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

The wires leading to and from a 0.12mmdiameter lightbulb filament are 1.5mm in diameter. The wire to the filament carries a current with a current density of role="math" localid="1648887651623" 4.5×105A/m2. What are (a) the current and (b) the current density in the filament?

The total amount of charge that has entered a wire at time tis given by the expressionQ=(20C)1-e-4(20s), where tis in seconds andt≥0.
a. Find an expression for the current in the wire at timet.
b. What is the maximum value of the current?
c. Graph Iversus tfor the interval 0≤t≤10s.

20. What electric field strength is needed to create a 5.0Acurrent in a 2.0-mm-diameter iron wire?

Suppose a time machine has just brought you forward from 1750(post-Newton but pre-electricity) and you've been shown the lightbulb demonstration of FIGURE Q27.1. Do observations or simple measurements you might make-measurements that must make sense to you with your 1700'sknowledge-prove that something is flowing through the wires? Or might you advance an alternative hypothesis for why the bulb is glowing? If your answer to the first question is yes, state what observations and/or measurements are relevant and the reasoning from which you can infer that something must be flowing. If not, can you offer an alternative hypothesis about why the bulb glows that could be tested?

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?
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