What is the behavior of current in a series resistive circuit?
A Constant
B Varies
C Divides
D Zero
In a series circuit, the current remains constant throughout all components. The same current flows through each resistor, as there is only one path for the current to travel.
What happens to the total impedance in a series circuit with resistors and inductors?
A Remains constant
B Increases
C Decreases
D Divides
In a series circuit with resistors and inductors, the total impedance increases. Impedance is the sum of the resistance and inductive reactance. Higher frequencies increase the inductive reactance, contributing to the overall impedance.
What is the main function of a capacitor in an AC circuit?
A Amplify signals
B Block current
C Store energy
D Regulate voltage
A capacitor stores energy in the form of an electric field. In AC circuits, it stores energy during one half of the cycle and releases it during the other half, which helps in smoothing and filtering signals.
What is the phase difference between voltage and current in a purely resistive AC circuit?
A 90 degrees
B 180 degrees
C 45 degrees
D 0 degrees
In a purely resistive AC circuit, the current and voltage are in phase, meaning their peak values occur at the same time. This occurs because resistors do not create any phase shift between current and voltage.
How does inductance affect current flow in an AC circuit?
A Decreases current
B Increases current
C Blocks current
D No effect
Inductance resists changes in current. In an AC circuit, it causes the current to lag behind the voltage. At higher frequencies, inductance increases, resulting in a greater opposition to the flow of current.
How does the impedance of a series circuit with a capacitor behave with frequency?
A Increases
B Decreases
C Stays constant
D Varies randomly
In a series circuit with a capacitor, the impedance decreases with increasing frequency. Capacitive reactance is inversely proportional to frequency, so higher frequencies reduce the total impedance.
What happens at resonance in an RLC circuit?
A Voltage increases
B Current becomes zero
C Impedance is minimized
D Current increases
At resonance, the inductive reactance and capacitive reactance cancel each other out, resulting in minimum impedance. This allows maximum current to flow through the circuit, making resonance a key concept in tuning circuits.
What does a phasor represent in an AC circuit?
A Frequency
B Current
C Voltage
D Complex amplitude
A phasor represents a sinusoidal waveform as a complex number, capturing both amplitude and phase. Phasors simplify the analysis of AC circuits, especially when dealing with voltage, current, and impedance in sinusoidal systems.
How does a transformer change the voltage in a circuit?
A Both
B Steps up
C Steps down
D None
A transformer can either step up or step down the voltage in an AC circuit, depending on the turns ratio of the primary and secondary coils. It works based on electromagnetic induction, transferring energy between circuits.
What happens to current in a parallel circuit as more resistors are added?
A Stays constant
B Increases
C Decreases
D Depends on voltage
In a parallel circuit, adding more resistors provides additional paths for current to flow, which reduces the overall resistance and causes the total current to increase, given the same supply voltage.
What is the effect of reducing the power factor in a circuit?
A Increases efficiency
B Decreases current
C Increases energy losses
D Reduces power
A low power factor means that a larger portion of the power supplied is reactive and does not perform useful work. This increases energy losses in the system and reduces the overall efficiency of power usage.
What is the primary function of a digital filter?
A Amplify signals
B Store energy
C Convert signals
D Remove unwanted frequencies
A digital filter is used to process signals by removing unwanted frequencies. It helps in applications such as noise reduction and signal conditioning, ensuring that only the desired frequencies pass through the system.
What is the role of feedback in an amplifier circuit?
A Control gain
B Increase power
C Decrease efficiency
D Control current
Feedback in an amplifier circuit controls the gain by feeding a portion of the output back to the input. This stabilizes the amplifier’s performance, reduces distortion, and helps achieve a desired output level.
What is the total impedance of a circuit with resistive and capacitive components in parallel?
A Always increases
B Depends on frequency
C Always decreases
D Depends on resistance
The total impedance of a parallel circuit with resistive and capacitive components depends on frequency. At higher frequencies, the capacitive reactance decreases, affecting the overall impedance of the circuit.
What does the power factor represent in an AC circuit?
A Ratio of current to voltage
B Efficiency of power usage
C Ratio of real power to apparent power
D Ratio of reactive power to real power
The power factor represents the ratio of real power (useful power) to apparent power (total power). A power factor of 1 means that all the power supplied is being used efficiently, while lower values indicate inefficiency due to reactive power.