What is transient analysis in an electrical circuit?
A Voltage change
B Long-term analysis
C Current behavior
D Immediate response
Transient analysis studies the short-term behavior of an electrical circuit during the period immediately following a change in the circuit, such as a sudden voltage change or when a circuit is switched on or off.
In a steady-state analysis, how are voltages and currents described?
A Constant
B Fluctuating
C Changing
D Zero
Steady-state analysis examines the behavior of a circuit after it has reached equilibrium, where voltages and currents are constant over time, and there are no transient effects or variations in the circuit.
What does the term “AC circuit” refer to?
A Fixed voltage
B Variable resistance
C Alternating current
D Direct current
An AC (alternating current) circuit is one where the current periodically reverses direction, unlike a DC (direct current) circuit where the current flows in only one direction. AC circuits are used in most power transmission systems.
What happens to the current in an AC circuit with inductance?
A Increases instantly
B Lags voltage
C Remains constant
D Leads voltage
In an AC circuit with inductance, the current lags the voltage. This is due to the inductor’s property of opposing changes in current, which causes a delay in the current reaching its peak relative to the voltage.
What is the effect of a capacitor in an AC circuit?
A Limits current
B Opposes voltage
C Shifts phase
D Stores energy
In an AC circuit, a capacitor causes a phase shift between the voltage and current. The current leads the voltage by 90 degrees in an ideal capacitive circuit, as the capacitor stores and releases energy during each cycle.
How does the impedance behave in an inductive AC circuit?
A Increases with frequency
B Varies randomly
C Decreases with frequency
D Remains constant
In an inductive AC circuit, the impedance increases with frequency because the inductive reactance increases with frequency. Higher frequencies result in greater opposition to current flow.
What happens to the voltage in a series AC circuit with resistive components?
A Remains constant
B Increases
C Varies randomly
D Divides equally
In a series AC circuit with resistive components, the total voltage from the source divides across the components according to their resistances. The voltage drop across each resistor is proportional to its resistance.
What defines a steady-state in an AC circuit?
A Random fluctuations
B No current flow
C Constant values of voltage and current
D Time-varying response
Steady-state in an AC circuit refers to the condition where the circuit has reached equilibrium, and the voltage and current values are constant, with no further transient behavior or changes occurring in the system.
In a transient analysis of a capacitor, what happens after it charges fully?
A Current stops
B Voltage increases
C Voltage decreases
D Current increases
Once a capacitor charges fully, the current in the circuit stops because the voltage across the capacitor becomes equal to the supply voltage. The capacitor behaves like an open circuit after being fully charged.
How does an inductor behave in an AC circuit at high frequencies?
A Acts as a short circuit
B Provides high impedance
C Provides low impedance
D Does not affect current
At high frequencies, an inductor offers high impedance because the inductive reactance increases with frequency. This limits the amount of current that can flow through the circuit at higher frequencies.
What is the phase relationship between voltage and current in a purely resistive AC circuit?
A Voltage leads current
B Current leads voltage
C Current and voltage are in phase
D Current and voltage are out of phase
In a purely resistive AC circuit, the current and voltage are in phase, meaning their peak values occur simultaneously. This is because resistors do not cause any phase shift between voltage and current.
What is the behavior of current in a purely capacitive AC circuit?
A Leads voltage
B In phase with voltage
C Lags voltage
D Opposes voltage
In a purely capacitive AC circuit, the current leads the voltage by 90 degrees. This happens because the capacitor continuously charges and discharges, with current flowing before the voltage reaches its peak.
What does resonance in an AC circuit occur when?
A Frequency is zero
B Resistance is at its maximum
C Voltage and current are out of phase
D Impedance is at a minimum
Resonance occurs in an AC circuit when the inductive reactance and capacitive reactance cancel each other out, resulting in minimum impedance. At this point, the circuit allows maximum current to flow.
What is the role of a resistor in an AC circuit?
A Change phase
B Limit current
C Control frequency
D Store energy
A resistor in an AC circuit limits the amount of current that can flow, regardless of the voltage. It dissipates energy as heat and does not affect the phase relationship between current and voltage.
How does a capacitor behave in a DC circuit?
A Conducts current
B Increases voltage
C Blocks current
D Changes resistance
In a DC circuit, a capacitor blocks current once it is fully charged. After charging, the capacitor behaves like an open circuit, preventing any further DC current flow.