What is Current Density?

 

 

Figure 2.3 a. Direct current (DC) b. Sinusoidal or alternating current (AC)

The current density (J) is the measure of the amount of current flowing through a unit area perpendicular to the direction of current flow. The boldfaced J is a vector whose magnitude is the current per unit area (A/m2) and whose direction is the direction of current flow.

Range of Currents

Can you think of some of the currents we encounter in our daily life?

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Currents in Our Daily Life

We encounter a wide range of currents in our daily life. Table 2.1 shows some examples of current ranging from high currents to very small currents. In the electrical power industry, for example, an ampere is a small unit. In an electronic circuit it is big unit for measuring current. Therefore, the milliampere (mA), one-thousandth of an ampere (0.001 A), or the microampere (µA), one-millionth of an ampere (0.000001 A), is used.

Table 2.1 Range of Currents


               

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