AC Circuit Analysis Quiz

Thevenin equivalent circuit is a simplified representation of a complex circuit. It consists of a single voltage source (VTH) and a series resistor (RTH). This equivalent circuit is used to find the current or voltage at any point in the original circuit by applying basic circuit analysis rules.

A node voltage is the voltage at a specific point (node) in the circuit relative to a reference point (often ground). It helps analyze the circuit and understand the voltage distribution.

A voltage source is an electrical component that provides a constant or variable voltage between its terminals, regardless of the current drawn. It's like a battery providing a set voltage.

A current source is an electrical component that supplies a constant or variable current to a circuit, regardless of the voltage across its terminals. It's like a pump pushing a constant amount of water through a pipe.

An RC differentiator is a circuit composed of a resistor (R) and a capacitor (C) connected in series. It differentiates the input signal, meaning it produces an output signal whose amplitude is proportional to the rate of change of the input signal.

An RC integrator is a circuit composed of a resistor (R) and a capacitor (C) connected in series. It integrates the input signal, meaning it produces an output signal whose amplitude is proportional to the area under the input signal curve.

An RL differentiator is a circuit composed of a resistor (R) and an inductor (L) connected in series. It differentiates the input signal, meaning it produces an output signal whose amplitude is proportional to the rate of change of the input signal.

An RL integrator is a circuit composed of a resistor (R) and an inductor (L) connected in series. It integrates the input signal, meaning it produces an output signal whose amplitude is proportional to the area under the input signal curve.

The voltage to which a capacitor will charge in an integrator circuit is determined by the input pulse voltage and the time constant of the circuit. This constant is the product of resistance and capacitance. The capacitor will charge towards the input voltage but not reach it fully due to the finite time constant of the circuit.

The output voltage of a differentiator circuit is proportional to the rate of change of the input voltage. This means that the output voltage will be highest when the input voltage changes rapidly and will be lowest when the input voltage changes slowly.

A leaky capacitor in an integrator will result in the circuit having a shorter time constant. This means the capacitor will charge faster, leading to a reduction in the amplitude of the output voltage and a distortion of the waveshape.

Thevenin's theorem is a technique used to simplify complex circuits by replacing a section of the circuit with a voltage source and a resistor in series. This approach aids in analyzing the circuit's behavior.

ZTH is the Thevenin equivalent impedance, representing the load seen by the circuit when looking from the output terminals with all sources turned off. It is essentially the resistance the circuit presents to the load.

In a circuit branch, if two currents flow in the same direction at any given moment, the total current at that instant is the sum of those two currents.

The Thevenin equivalent voltage (VTH) is the open-circuit voltage across the output terminals. To find it, imagine disconnecting the load and calculating the voltage across the open terminals.

Thevenin's theorem allows us to replace a complex circuit with a simpler equivalent circuit consisting of a single voltage source (VTH) and a series resistor (RTH). This simplifies analysis, making it easier to determine the current or voltage at any point in the original circuit.

The Thevenin resistance (RTH) is the equivalent resistance seen by the load when all independent voltage sources are shorted and independent current sources are opened.

The Thevenin voltage (VTH) is the open-circuit voltage across the load terminals when it is disconnected from the rest of the circuit.

The resonant frequency (fr) in a parallel RLC circuit is the frequency at which the impedance is maximum. It is the frequency where the inductive and capacitive reactances cancel each other out.

The bandwidth (BW) of a resonant circuit is the range of frequencies over which the circuit's output power is greater than half its maximum power. It's essentially the width of the frequency response curve.

A low-pass filter allows low-frequency signals to pass through while attenuating (weakening) high-frequency signals. Think of it as a filter that lets low-frequency waves pass through while blocking higher-frequency ones.

The critical frequency (fc) of a low-pass filter is the frequency at which the output voltage is reduced to 70.7% or 1/sqrt(2) of the input voltage. Think of it as the frequency where the filter starts to significantly attenuate the signal.

A high Q-factor in a series resonant circuit indicates that the circuit is very selective, meaning that it only allows a narrow range of frequencies to pass through.Think of it as a very picky filter.

Capacitors connected in series have a total capacitance less than the smallest individual capacitance.

The capacitance of a capacitor increases when the plate area is increased.

Capacitive reactance (Xc) is the opposition to current flow due to a capacitor. It's calculated as 1 / (2πfC), where f is the frequency and C is the capacitance.

At the instant a switch is closed in a circuit with a capacitor, the capacitor acts like a short circuit, so the voltage across it is 0V.

When the voltage across a capacitor triples, the stored charge also triples.

In a series RL circuit, increasing the frequency causes the inductive reactance (XL) to increase. This leads to a higher impedance, resulting in a decrease in current flow.

The phase angle in a parallel circuit with a capacitor and resistor is determined by the difference in phase between the current through the capacitor and the current through the resistor. The capacitor leads the voltage by 90 degrees, while the resistor has no phase shift.

Resistors connected in parallel have a total resistance less than the smallest individual resistance.

The current flow through a circuit with resistors in series is the same throughout the entire circuit.

The total admittance of a parallel RL circuit is the sum of the individual admittances of the resistor and the inductor. Admittance is the reciprocal of impedance, and impedance in a parallel circuit is calculated using the formula: 1/Z = 1/R + 1/XL.

When the frequency is decreased, the inductive reactance of a parallel RL circuit also decreases. This leads to a lower impedance, and therefore, a higher current flow.

The power dissipated by multiple components connected in parallel is the sum of the individual power dissipations.

In a series RL circuit, the impedance is calculated using the formula: Z = √(R² + XL²), where R is the resistance and XL is the inductive reactance. The phase angle is calculated using the formula: θ = arctan(XL/R).

The current through an inductor in a parallel circuit is determined by the voltage across the inductor and its inductive reactance. The formula used is I = V/XL, where I is the current, V is the voltage, and XL is the inductive reactance.

A parallel RL circuit is a circuit that has a resistor (R) and an inductor (L) connected in parallel to a voltage source. The current through each component is determined by their respective impedance.

The current flowing through the resistor in a parallel RC circuit is determined by the voltage across the resistor and its resistance. The formula used is I = V/R, where I is the current, V is the voltage, and R is the resistance.

The force that opposes the establishment of a magnetic field in a material is called reluctance. It can be defined as the ratio of magnetomotive force (mmf) to the magnetic flux (Φ) in the material, expressed as R = mmf / Φ. Reluctance is analogous to resistance in electrical circuits, hindering the flow of magnetic flux.

In a three-wire Y-connected generator, the line voltages are √3 times greater than the phase voltages. This is due to the 120° phase difference between the phase voltages. Therefore, the line voltage magnitude is √3 * 2000 V = 3464 V.

The unit of flux density, also known as magnetic field strength, is the Tesla (T). It's defined as the amount of magnetic flux passing through a unit area perpendicular to the direction of the flux.

A solenoid is an electromagnetic device with a movable iron core, often referred to as a plunger, that moves within a coil. It utilizes electromagnetism to convert electrical energy into mechanical energy, moving the plunger based on the applied current.

Hysteresis describes the lagging of a magnetic material's magnetization behind the application of a magnetizing force (also known as the magnetizing field). It means the magnetization doesn't change instantaneously with the applied force, but rather trails it.

When a magnetic field collapses, the polarity of the induced voltage reverses. This phenomenon is explained by Lenz's law, which states that the induced current opposes the change in magnetic flux. As the field weakens, the induced voltage creates a current that tries to maintain the field, resulting in the reversal of polarity.

In a Δ-connected source feeding a Y-connected load, each phase voltage in the source is equal to the corresponding load voltage. This is because the line voltages in a Δ-connected source are equal to the phase voltages, and the line voltages in a Y-connected load are equal to the phase voltages multiplied by √3. Therefore, the phase voltages match.

In a Y-Y source/load configuration, the phase current, line current, and load current are all equal in each phase. This is because the line current is equal to the phase current in both the source and the load.