Reactance is the opposition to the flow of alternating current (AC) caused by capacitors and inductors. Unlike resistance, reactance changes with the frequency of the AC signal, and it can be inductive or capacitive.
In a series RLC circuit, what happens at resonance?
A Current is zero
B Voltage is maximum
C Resistance is zero
D Impedance is minimum
At resonance in a series RLC circuit, the inductive and capacitive reactances cancel each other out, resulting in the minimum impedance. This allows the maximum current to flow through the circuit.
How does inductive reactance change with frequency?
A Increases
B No effect
C Decreases
D Constant
Inductive reactance is directly proportional to the frequency of the AC signal. As the frequency increases, the inductive reactance increases, making it harder for current to flow through an inductor.
What is the effect of increasing the capacitance in a capacitive AC circuit?
A Increases reactance
B No effect
C Decreases reactance
D Constant power
In a capacitive AC circuit, increasing the capacitance decreases the capacitive reactance. This allows more current to flow through the circuit, as reactance is inversely proportional to capacitance.
What does a coupled circuit involve?
A Constant power
B Zero voltage
C Single current path
D Mutual inductance
A coupled circuit involves two or more inductors that influence each other through mutual inductance. This occurs when the magnetic field generated by one inductor induces a voltage in another, affecting the overall circuit behavior.
What is the behavior of the total impedance in a parallel RLC circuit at resonance?
A Infinite impedance
B Minimum impedance
C Zero impedance
D Maximum impedance
At resonance in a parallel RLC circuit, the impedance is minimized, allowing the maximum current to flow through the circuit. The inductive and capacitive reactances cancel out, creating a purely resistive path.
What is true about the total reactance in a series RLC circuit at resonance?
A Zero reactance
B Negative reactance
C Maximum reactance
D Equal to resistance
At resonance in a series RLC circuit, the inductive and capacitive reactances cancel each other out, resulting in zero total reactance. This allows maximum current to flow through the circuit, limited only by the resistance.
What is the effect of increasing the frequency on capacitive reactance in an AC circuit?
A No effect
B Increases reactance
C Becomes infinite
D Decreases reactance
Capacitive reactance is inversely proportional to the frequency of the AC signal. As the frequency increases, the capacitive reactance decreases, allowing more current to flow through the capacitor.
How does reactance affect the phase relationship between voltage and current?
A Current leads voltage
B Voltage and current are at 90°
C No phase shift
D Voltage leads current
In circuits with reactance (inductive or capacitive), the voltage and current are typically out of phase. In an inductor, the current lags the voltage by 90°, while in a capacitor, the current leads the voltage by 90°.
What happens to the current in a parallel RLC circuit when the impedance is low?
A Zero current
B Decreases
C Increases
D Remains constant
In a parallel RLC circuit, when the impedance is low (as at resonance), the current increases. This is because low impedance provides a path of least resistance for the current to flow through.
In a series RLC circuit, what happens if the inductive reactance is greater than the capacitive reactance?
A The circuit becomes inductive
B Current is maximum
C The impedance becomes zero
D The current is capacitive
If the inductive reactance is greater than the capacitive reactance in a series RLC circuit, the circuit behaves inductively. This results in a positive phase shift, where the current lags the voltage.
What happens in a series RLC circuit when the capacitive reactance exceeds the inductive reactance?
A The impedance is zero
B The current lags the voltage
C The current leads the voltage
D The circuit becomes inductive
When the capacitive reactance exceeds the inductive reactance in a series RLC circuit, the circuit behaves capacitively. This results in a negative phase shift, where the current leads the voltage.
What does the resonance frequency in an RLC circuit depend on?
A Current
B Voltage
C Capacitance and inductance
D Resistance
The resonance frequency in an RLC circuit is determined by the values of the inductance (L) and capacitance (C). It is given by the formula f₀ = 1 / (2π√(LC)), where f₀ is the resonance frequency.
How do coupled inductors influence each other in a circuit?
A Induced voltage
B Increase total resistance
C No influence
D Decrease total current
Coupled inductors influence each other through mutual inductance. When the magnetic field of one inductor changes, it induces a voltage in the other inductor. This interaction can affect the overall behavior of the circuit.
What happens to the total impedance in a parallel RLC circuit as the frequency moves away from resonance?
A Remains constant
B Decreases
C Increases
D Becomes zero
In a parallel RLC circuit, as the frequency moves away from resonance, the impedance increases. This occurs because the inductive and capacitive reactances no longer cancel each other out, resulting in higher total impedance.