What does transient analysis in an electrical circuit focus on?
A Circuit behavior during steady-state
B Circuit behavior after a sudden change in conditions
C Current and voltage at peak values
D The energy stored in inductive components
**Transient analysis** is used to study the behavior of a circuit when there is a sudden change in voltage or current, such as when a switch is turned on or off. It examines how the circuit responds to these changes over time.
What is the steady-state condition in an electrical circuit?
A The voltage and current are changing continuously
B The current and voltage reach constant values
C The current is zero
D The components store energy
**Steady-state** refers to the condition in which the voltage and current in a circuit have stabilized and no longer change with time. This is the behavior after transient effects have settled.
In an AC circuit, what is the purpose of using phasors?
A To simplify voltage measurements
B To represent sinusoidal waveforms as complex numbers
C To analyze DC circuits
D To calculate the total energy stored
**Phasors** represent sinusoidal waveforms as complex numbers, which simplifies the analysis of AC circuits. Phasors are particularly useful in solving circuits involving multiple frequencies.
What does impedance in an AC circuit combine?
A Resistance and capacitance
B Resistance and voltage
C Resistance and reactance
D Reactance and current
**Impedance** is the total opposition to current flow in an AC circuit. It combines **resistance** (R) and **reactance** (X), which can be either inductive reactance (XL) or capacitive reactance (XC).
What is the purpose of admittance in AC circuits?
A To represent how easily current flows through a circuit
B To calculate voltage drops
C To measure resistance in an AC circuit
D To store energy in the circuit
**Admittance** is the reciprocal of **impedance** in an AC circuit. It represents how easily current can flow in the circuit and is measured in **siemens (S)**.
How does the resonance in an RLC circuit affect current?
A It increases the impedance
B It maximizes the current
C It decreases the current
D It reduces the frequency
At **resonance** in an **RLC circuit**, the inductive and capacitive reactances cancel each other out, leading to a minimum impedance and a maximum current.
What happens to the impedance in a purely inductive AC circuit?
A It decreases with frequency
B It increases with frequency
C It is constant
D It is zero
In a **purely inductive AC circuit**, the **impedance** increases with frequency because the **inductive reactance (XL)** increases with frequency.
In a series RLC circuit at resonance, what is the total impedance?
A Maximum
B Equal to the resistance
C Infinite
D Zero
At **resonance** in a **series RLC circuit**, the **inductive reactance** and **capacitive reactance** cancel each other out, leaving only the **resistance (R)**. Thus, the total impedance equals the resistance.
What is the formula for calculating the impedance of a series RLC circuit?
A Z = R + XL + XC
B Z = √(R² + (XL – XC)²)
C Z = R + j(XL – XC)
D Z = R + j(XC – XL)
The impedance **Z** of a **series RLC circuit** is given by **Z = √(R² + (XL – XC)²)**, where **R** is the resistance, **XL** is the inductive reactance, and **XC** is the capacitive reactance.
What is the impact of resonance in an RLC circuit on the impedance?
A The impedance is minimized
B The impedance is maximized
C The impedance is constant
D The impedance becomes zero
At **resonance** in an **RLC circuit**, the **impedance** is minimized because the inductive and capacitive reactances cancel each other out, allowing maximum current to flow.
What is the primary purpose of **admittance** in AC circuit analysis?
A To represent how easily current flows through the circuit
B To calculate the total power in the circuit
C To store energy in the circuit
D To calculate the resistance
**Admittance** is the reciprocal of **impedance** and represents how easily current can flow in an AC circuit. It is useful for simplifying calculations in AC analysis.
What is the result of adding more resistors in **series** with the existing resistors?
A The total resistance increases
B The total resistance decreases
C The total current decreases
D The total current increases
In a **series circuit**, adding more resistors increases the total resistance because the resistances are summed up.
What is the effect of increasing the frequency in a **capacitive** AC circuit?
A The capacitive reactance increases
B The capacitive reactance decreases
C The impedance increases
D The voltage increases
In a **capacitive** AC circuit, **capacitive reactance (XC)** decreases as the frequency increases, because **XC = 1 / (2πfC)**.
What is the effect of resonance on current in an **RLC** circuit?
A The current increases
B The current decreases
C The current remains the same
D The current becomes zero
At **resonance**, the impedance is minimized, and the current is maximized because the inductive and capacitive reactances cancel each other out.
In a **resonant** RLC circuit, what happens to the impedance when the frequency is above resonance?
A The impedance increases
B The impedance decreases
C The impedance remains the same
D The current increases
Above **resonance**, the **capacitive reactance** becomes larger than the **inductive reactance**, causing the total impedance to increase.
What is the result of **adding more resistors in parallel** in an AC circuit?
A The total current decreases
B The total current increases
C The total impedance decreases
D The voltage increases
In a **parallel circuit**, adding more resistors provides additional paths for the current, increasing the total current and decreasing the total resistance.
What does the **power factor** in an AC circuit tell you?
A The efficiency of the circuit in using power
B The voltage drop in the circuit
C The total current
D The energy storage capacity
**Power factor** indicates how efficiently the circuit uses the power supplied. A power factor of 1 means the circuit is using all the supplied power effectively.
What is the total current in a **parallel circuit** when the total resistance decreases?
A The current increases
B The current decreases
C The current remains the same
D The current becomes zero
In a **parallel circuit**, adding more resistors decreases the total resistance, which allows more current to flow.
What is the **primary function** of a **transformer** in an electrical circuit?
A To increase or decrease voltage
B To store electrical energy
C To regulate the current
D To convert AC to DC
A **transformer** is used to **increase or decrease** the voltage level in an AC circuit while keeping the power constant.
What happens to the **total impedance** in a series RLC circuit when the frequency is below resonance?
A The impedance decreases
B The impedance increases
C The current decreases
D The current increases
Below resonance, the **capacitive reactance** is greater than the **inductive reactance**, which increases the total impedance.