AC Performance Characteristics

What is the power factor of an ideal inductor in an AC circuit?

• 2

• 1

• 0

• 0.5

Explain the concept of impedance in AC circuits.

• Impedance in AC circuits is the same as DC resistance.

• Impedance is only related to resistance in AC circuits.

• Impedance in AC circuits is the total opposition to the flow of alternating current. It consists of resistance, inductive reactance, and capacitive reactance.

• Impedance in AC circuits does not involve inductive or capacitive reactance.

How does frequency affect the reactance of a capacitor in an AC circuit?

• The reactance of a capacitor becomes negative.

• The reactance of a capacitor remains constant.

• The reactance of a capacitor decreases.

• The reactance of a capacitor increases.

What is the phase relationship between voltage and current in a purely resistive AC circuit?

• Inverted phase

• Out of phase

• 180 degrees out of phase

• In phase

Define resonance in the context of AC circuits.

• Resonance is when resistance dominates the circuit

• Resonance occurs when the frequency is too high for the circuit to handle

• Resonance is only applicable to DC circuits

• Resonance in AC circuits is when inductive and capacitive reactances cancel each other out, resulting in a net impedance of zero.

What is the significance of the power triangle in AC circuits?

• It helps in understanding the relationship between real power, reactive power, and apparent power in AC circuits.

• It measures the voltage drop across components in the circuit

• It determines the frequency of the AC signal

• It represents the resistance, inductance, and capacitance values in the circuit

Discuss the impact of harmonics on AC power systems.

• Harmonics improve the efficiency of AC power systems

• Harmonics have no impact on AC power systems

• Harmonics only affect DC power systems

• Harmonics can negatively impact AC power systems by causing overheating, energy losses, interference, and waveform distortion.

Explain the difference between real power and reactive power in AC circuits.

• Real power is the power consumed by imaginary elements in the circuit, while reactive power is the actual power in watts.

• Real power is the power consumed by the load, while reactive power is the power supplied by the source.

• Real power is measured in volt-amperes reactive (VAR), while reactive power is measured in watts.

• Real power is the actual power consumed by the circuit in watts, while reactive power is the power oscillating between the source and load due to inductive or capacitive elements in the circuit, measured in volt-amperes reactive (VAR).

How does the presence of a neutral wire affect AC power distribution?

• Neutral wire increases resistance in AC power distribution.

• Neutral wire causes power surges in AC power distribution.

• Neutral wire blocks the flow of current in AC power distribution.

• Neutral wire provides a path for current to return to the source in AC power distribution.

What are the advantages of using three-phase power in AC systems?

• Constant and balanced power supply, smaller and lighter motors, higher efficiency for high-power applications

• Larger and heavier motors

• Unstable power supply

• Lower efficiency for high-power applications