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The units of specific contact resistivity are typically therefore in ohm-square metre, or Ω⋅m 2. When the current is a linear function of the voltage, the device is said to have ohmic contacts . Inductive and capacitive methods could be used in principle to measure an intrinsic impedance without the complication of contact resistance.
Consider a direct-current circuit with a nine-volt DC source; three resistors of 67 ohms, 100 ohms, and 470 ohms; and a light bulb—all connected in series. The DC source, the conductors (wires), the resistors, and the light bulb (the load) all have resistance; all use and dissipate supplied energy to some degree. Their physical ...
When a metal wire is subjected to electric force applied on its opposite ends, these free electrons rush in the direction of the force, thus forming what we call an electric current. More technically, the free electron model gives a basic description of electron flow in metals.
American EIA standard RS-299A specifies that (or DCR) should be at least 80% of the rated driver impedance, so an 8-ohm rated driver should have a DC resistance of at least 6.4 ohms, and a 4-ohm unit should measure 3.2 ohms minimum. This standard is voluntary, and many 8-ohm drivers have resistances of ≈5.5 ohms, and proportionally lower for ...
In the power systems analysis field of electrical engineering, a per-unit system is the expression of system quantities as fractions of a defined base unit quantity. . Calculations are simplified because quantities expressed as per-unit do not change when they are referred from one side of a transformer to t
A voltage divider referenced to ground is created by connecting two electrical impedances in series, as shown in Figure 1. The input voltage is applied across the series impedances Z 1 and Z 2 and the output is the voltage across Z 2. Z 1 and Z 2 may be composed of any combination of elements such as resistors, inductors and capacitors.
The result is a reasonable tolerance (0.5%, 1%, or 2%) and a temperature coefficient that is generally between 50 and 100 ppm/K. [9] Metal film resistors possess good noise characteristics and low non-linearity due to a low voltage coefficient. They are also beneficial due to long-term stability.