电功率，电能和理想电源 | Power, Energy, Ideal Sources
电功率 | Power
p = dw / dt = vi = v2 / R = i2R
Unit: Watt (W)
理想电压 / 电流源 | Ideal Voltage / Current Sources
The Ideal Voltage Source
保持恒定电压的电源
An ideal voltage source is an ideal circuit element that maintains a prescribed voltage across its terminals at all times, regardless of the current flowing in those terminals.
The Ideal Current Source
保持恒定电流的电源
An ideal current source is an ideal circuit element that maintains a prescribed current through its terminals at all times, regardless of the voltage across those terminals.
直流电路 | Direct Current (DC) Circuits
The currents and voltages remain constant everywhere.
开路 | The open circuit
An ideal current source with a value equal to zero is a device that has 0 A of current on it. In other words, it doesn’t pass any current, no matter how large or how small the voltage v is. (电流恒等于零)
It is equivalent to an open circuit.
短路 | The short circuit
An ideal voltage source with a value equal to zero is a device that has 0 V of voltage on it, no matter how large or how small the voltage v is. (电压恒等于零)
It is equivalent to a piece of perfect conductor, also called a short circuit.