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6: Steady Current and Conductivity
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- 6.1: Convection and Conduction Currents
- In practice, we deal with two physical mechanisms for current: convection and conduction. The distinction between these types of current is important in electromagnetic analysis.
- 6.2: Current Distributions
- The convention in electrical engineering defines positive current as the flow of positive charge into the positive voltage terminal of a passive device such as a resistor, capacitor, or inductor. For an active device such as a battery, positive current corresponds to the flow of positive charge out of the positive voltage terminal.
- 6.3: Conductivity
- Conductivity is one of the three primary “constitutive parameters” that is commonly used to characterize the electromagnetic properties of materials . Conductivity is a property of materials that determines conduction current density in response to an applied electric field.
- 6.4: Resistance
- The concept of resistance is most likely familiar to readers via Ohm’s Law for Devices; i.e., V=IR where V is the potential difference associated with a current I . This is correct, but it is not the whole story.
- 6.5: Conductance
- Conductance, like resistance, is a property of devices. Therefore, conductance depends on both the conductivity of the materials used in the device, as well as the geometry of the device.
- 6.6: Power Dissipation in Conducting Media