CH 7_BOOK_FIRST ORDER CIRCUITS Flashcards
Applying Kirchhoff’s laws to purely resistive circuits results in algebraic equations, while applying the laws to RC and RL circuits produces ___________ equations.
Differential
A first-order circuit is characterized by a first-order __________ equation.
Differential
Regarding the 4 possible situations studied in this chapter: What are the 2 types of first-order circuits? What are the 2 ways to excite them?
RC and RL.
- Initial conditions of the storage elements in the circuits (source-free).
- Independent sources.
How does energy behave in source-free circuits?
Without independent sources, we assume that energy is initially stored in the capacitive or inductive element. The energy causes current to flow in the circuit and is gradually dissipated in the resistors.
T/F: Source-free circuits are free of independent sources but they may have dependent soruces.
True
How do you define a circuit response?
A circuit response is the manner in which the circuit reacts to an excitation.
For Source-free RC circuits, what is the formula for voltage?
Define the “natural response” of a Source-free RC circuit.
The natural response of a circuit refers to the behavior (in terms of voltages and currents) of the circuit itself, with no external sources of excitation.
What is the circuit response in a Source-free RC circuit? What kind of response is it?
The voltage across the capacitor.
A natural response (due to the initial energy stored and the physical characteristics of the circuit, not due to some external voltage or current source).
VIEW: The voltage response of the RC circuit.
7.2. Note that at t = 0, we have the correct initial condition as in Eq. (7.1). As t increases, the voltage decreases toward zero. The rapidity with which the voltage decreases is expressed in terms of the time constant, denoted by τ, the lowercase Greek letter tau.
What is the time constant of a Source-free RC circuit?
The time constant of a circuit is the time required for the response to decay to a factor of 1/e or 36.8 percent of its initial value.
For Source-free RC circuits, what is the formula for time constant?
In Source-free RC circuits, it is customary to assume that the capacitor is fully discharged after how many time constants?
5
VIEW: Values of v(t)/V(0)
VIEW: Graphical determination of the time constant from the response curve.
For Source-free RC circuits, what is the formula for the current through the resistor?
For Source-free RC circuits, what is the formula for the power dissipated in the resistor?
For Source-free RC circuits, the formula for the energy absorbed by the resistor up to time t is?
In Source-free RC circuits, what happens as t -> infinity with regards to energy?
What are the 2 keys to working with a Source-Free RC circuit?
What can be obtained from these 2 values?
- Finding the initial voltage v(0) across the capacitor.
- Finding the time constant.
When finding the time constant in Source-free RC circuits, R is often the?
The Thevenin equivalent resistance at the terminals of the capacitor (take out the capacitor C and find R = R_th at its terminals.
For Source-free RL circuits, what is the formula for current?
For Source-free RL circuits, what is the formula for the time constant?
For Source-free RL circuits, what is the formula for the voltage across the resistor?
For Source-free RL circuits, what is the formula for the power dissipated in the resistor?
For Source-free RL circuits, the formula for the energy absorbed by the resistor up to time t is?
In Source-free RL circuits, what happens as t -> infinity with regards to energy?
What are the 2 keys to working with a Source-Free RL circuit?
What can be obtained from these 2 values?
- The initial current i(0) through the inductor.
- The time constant of the circuit.
When finding the time constant in Source-free RL circuits, R is often the?
The Thevenin equivalent resistance at the terminals of the inductor.
