Linear resistive element → When the voltage and current take the relevant reference direction, the voltage and current at both ends obey Ohm's law at any time The u~i relationship → satisfies Ohm’s law Unit→R is resistance, G is conductance

Resistor open circuit and short circuit ·Open circuit: the current is not 0 and the voltage is 0 → the resistance is infinite and the conductance is 0 ·Short circuit: The current is 0 and the voltage is not 0 → the resistance is 0 and the conductance is infinite 0

Power and energy: p>0, the resistor power is always a non-negative number, the resistor element always consumes power at any time, and is a passive element (an element that never provides energy to the external circuit)

Properties of an ideal voltage source: a. The terminal voltage is determined by the power supply itself and has nothing to do with the external circuit. b. The current passing through it is arbitrary and determined by the external circuit.

Properties of an ideal current source: a. The power supply current of the current source is determined by the power supply itself and has nothing to do with the external circuit. b. The voltage across the current source is arbitrary and determined by the external circuit.

Definition → A model abstracted from electronic components is a dual-port component. One port is a control branch (open circuit or short circuit), and the other port is a controlled branch (having the properties of a voltage source or current source), and its voltage or current is controlled by the control branch voltage (or current).

Classification: According to whether the control quantity is voltage or current, there are 4 types of controlled sources 1. Current Controlled Current Source (CCCS) 2. Current controlled voltage source (CCVS) 3. Voltage controlled voltage source (VCVS) 4. Voltage controlled current source (VCVS)

Comparison of controlled and independent sources: ●The independent source voltage (or current) is determined by the power supply itself and has nothing to do with other voltages and circuits in the circuit, while the controlled source voltage (or current) is determined by the control quantity. ●The independent source plays the role of "excitation" in the circuit and generates voltage and current in the circuit. The controlled source reflects the control relationship between the voltage or current in one place in the circuit and the voltage or current in another place. It cannot be used in the circuit. as "incentive".

Including Kirchhoff's current law (KCL) and Kirchhoff's voltage law (KVL)

noun 1. Branch → A branch in a circuit that passes the same current. 2. Node → The connection point of three or more branches is called a node. 3. Path → a path between two nodes, consisting of branches. 4. Loop → a closed path composed of branches. 5. Mesh → For planar circuits, the loop that does not contain any branches inside is called a mesh. (A mesh is a loop but a loop is not necessarily a mesh)

Kirchhoff's current law (KCL) At any node in the lumped parameter circuit, at any time, the algebraic sum of the branch currents connected to that point is 0. (This shows that KCL can be generalized to any closed surface surrounding multiple nodes in the circuit)

Kirchhoff's Voltage Law (KVL) In a lumped parameter circuit, at any time, along any loop, the algebraic sum of all branch voltages is always equal to zero. a. Calibrate the voltage reference direction of each component; b. Select the loop detour direction, clockwise or counterclockwise

Actual circuit → designed to accomplish an intended purpose, Installation, operation, interaction between circuit components and circuit devices connected current path device

Circuit model (circuit)

1. Reference direction of current

Reference direction of voltage

Electric power: work done by electric field force per unit time (unit W)

Energy (unit J)

Circuit component → the most basic unit in the circuit Component characteristics: The two terminals of the component Algebraic functional relationships between circuit physical quantities. Note: If the mathematical relationship that characterizes the terminal characteristics of a component is a linear relationship, the component is called a linear component, otherwise it is called non-linear components.

lumped parameter circuit Lumped condition → the length is much larger than the electromagnetic wavelength Lumped element → at any time, the flow into the two-terminal element The current flowing from one terminal must be equal to the current flowing from the other terminal The current flowing out, and the voltage between the two terminals is a single value. Lumped parameter circuit → circuit composed of lumped elements