Search results
Results From The WOW.Com Content Network
In this type the resistance varies with the applied voltage or current. Negative resistance vs positive resistance: If the I–V curve has a positive slope (increasing to the right) throughout, it represents a positive resistance. An I–V curve that is nonmonotonic (having peaks and valleys) represents a device which has negative resistance.
In modern notation we would write, = +, where is the open-circuit emf of the thermocouple, is the internal resistance of the thermocouple and is the resistance of the test wire. In terms of the length of the wire this becomes, I = E r + R ℓ , {\displaystyle I={\frac {\mathcal {E}}{r+{\mathcal {R}}\ell }},} where R {\displaystyle {\mathcal {R ...
The load resistance can often be varied rapidly in order to test the power supply's transient response. Just like a resistor, an active load converts the power supply's electrical energy to heat. The heat-dissipating devices (usually transistors ) in an active load therefore have to be designed to withstand the resulting temperature rise, and ...
[citation needed] For example, the internal structure of an NPN bipolar transistor resembles two P-N junction diodes connected together by a common anode. In normal operation the base-emitter junction does indeed form a diode, but in most cases it is undesirable for the base-collector junction to behave as a diode.
In practice, the internal resistance of a battery is dependent on its size, state of charge, chemical properties, age, temperature, and the discharge current. It has an electronic component due to the resistivity of the component materials and an ionic component due to electrochemical factors such as electrolyte conductivity , ion mobility ...
In this case, Z L >> Z S, (in practice:) DF > 10 In video, RF, and other systems, impedances of inputs and outputs are the same. This is called impedance matching or a matched connection. In this case, Z S = Z L, DF = 1/1 = 1 . The actual output impedance for most devices is not the same as the rated output impedance.
No physical current source is ideal. For example, no physical current source can operate when applied to an open circuit. There are two characteristics that define a current source in real life. One is its internal resistance and the other is its compliance voltage. The compliance voltage is the maximum voltage that the current source can ...
A more refined model also includes a resistance in series with the voltage source to represent the battery's internal resistance (which results in the battery heating and the voltage dropping when in use). A current source in parallel may be added to represent its leakage (which discharges the battery over a long period).