Question Bank: ALTERNATING CURRENT

What is the primary reason alternating current (AC) is preferred over direct current (DC) in electrical systems?

What type of waveform does the voltage supply from typical household mains represent?

Which of the following devices primarily uses alternating current?

What is meant by 'AC voltage' in simple harmonic motion?

When the AC voltage across a resistor increases, what happens to the current through the resistor?

What is the average current through a resistor over one complete cycle of AC?

In AC circuits, the relationship between voltage and current is characterized by what term?

Which scientist is credited with major contributions to the development of AC technology?

What is the significance of transformers in AC systems?

In sinusoidal AC circuits, if the voltage is given by V(t) = Vm sin(ωt), what does Vm represent?

Which of the following best describes the phase relationship in a pure resistive AC circuit?

How does the waveform of AC differ from DC?

What is the formula for the current through a resistor when an AC voltage is applied?

What effect does increasing the frequency have on the impedance in a purely capacitive AC circuit?

What happens to the average current over one complete cycle in an AC circuit with a resistor?

In an AC circuit with both resistance and inductance, what happens to the phase of the current relative to the voltage?

If the maximum AC voltage applied to a resistor is doubled, how does the maximum current change?

Which of the following phenomena arises from the alternating nature of AC?

What is the relationship between voltage and current in a pure resistor when AC is applied?

How is the power dissipated in a resistor due to AC current expressed mathematically?

What does the term 'RMS current' refer to in AC circuits?

What is the phase difference between voltage and current in a resistor when alternating current is applied?

If the average power dissipated in a resistor is given by P = I_rms^2 R, which term represents the RMS value of current?

In an AC circuit with a resistor, what happens to the instantaneous power when the current is minimum?

What is the average value of AC power over one complete cycle through a resistor?

When current is at its peak in an AC circuit, the corresponding voltage is also at its peak. What is this relationship called?

In an AC circuit, a resistor with resistance R is connected to an AC voltage source. If R is halved, what happens to the RMS current?

According to Joule's heating law, the rate of heat produced in a resistor due to AC current is proportional to which of the following?

When analyzing AC circuits, which peak current value is often used to determine average power?

What impact does alternating current have on the resistance of a pure resistor?

If an AC voltage source produces a sinusoidal voltage with an angular frequency ω, what is the expression for the instantaneous voltage?

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

What is the formula for the inductive reactance (X_L) in an AC circuit?

If the peak voltage across an inductor is 10 V and its inductance is 2 H, what is the peak current?

In the phasor diagram of a purely inductive circuit, which way does the current phasor point relative to the voltage phasor?

Which law explains the negative sign in the equation d(v)/dt = -L(d(i)/dt) for an inductor?

How does increasing the frequency of the AC source affect the inductive reactance?

What is the unit of inductive reactance?

What happens to the current in an inductor when a DC source is suddenly turned on?

If the voltage across an inductor is given by v(t) = V_m sin(ωt), how can we express the current i(t)?

For a given inductor, how does the inductive reactance change if the inductance is doubled?

In a phasor diagram, what does the vertical component of a phasor represent?

If the frequency of the AC source is halved, what happens to the inductive reactance?

The energy stored in an inductor is given by which formula?

Which of the following describes the behavior of current through a purely inductive circuit when AC voltage is applied?

In which scenario would the inductance of an inductor effectively reduce in a circuit with alternating current?

What does a phasor represent in an AC circuit?

In a purely resistive AC circuit, the phase difference between current and voltage is:

What is the effect of an inductor on the phase of AC current compared to AC voltage?

The current through a capacitor in an AC circuit is described as leading the voltage by how many degrees?

The projection of a phasor on the vertical axis represents which of the following?

In a series RLC circuit, if the inductive reactance equals capacitive reactance, what phenomenon occurs?

How are vectors in a phasor diagram typically represented?

What is the primary purpose of using phasors in AC circuit analysis?

In a phasor diagram, if the current phasor is represented as I, what would the voltage phasor across a capacitor be denoted as?

Which of the following is true for the average power in a purely inductive circuit?

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

In the context of phasors, what does the term 'angular speed' refer to?

How does the phase angle affect the power factor in an AC circuit?

In RLC circuits, what does the term 'impedance' refer to?

What condition must be met for resonance to occur in a series RLC circuit?

Which of the following statements about phasors is incorrect?

What is the power factor in a purely resistive AC circuit?

In an RLC circuit with a phase angle φ, the average power is proportional to which of the following?

What happens to the power factor in a purely inductive circuit?

What is the effect of a low power factor in an electrical system?

How is the power factor defined mathematically in an AC circuit?

In a series RLC circuit, if the resistance is halved while keeping voltage constant, what happens to the power factor?

What type of current do you have in a purely capacitive circuit?

In what conditions is the power factor equal to zero?

Which of the following correctly defines the average power in an AC circuit using voltage, current, and power factor?

If the voltage in an AC circuit is increased while keeping the power factor constant, what happens to the average power?

In an LCR circuit with a power factor of 0.5, what is the relationship between real power and apparent power?

Under what condition does maximum power transfer occur in an AC circuit?

What is the average power in an AC circuit with RMS voltage V and RMS current I, if the power factor is zero?

What happens to the current in a capacitor when connected to an AC voltage source?

How is the instantaneous voltage across a capacitor in an AC circuit expressed mathematically?

What is the capacitive reactance (X_c) in an AC circuit?

What type of waveform does the voltage across a capacitor exhibit when connected to an AC source?

If the capacitance of a capacitor is tripled while keeping the frequency constant, what happens to the capacitive reactance?

What is the phase difference between the current and voltage in a purely capacitive AC circuit?

For an AC circuit with a capacitor, if the frequency is doubled, what happens to the capacitive reactance?

What is the effect of increasing the voltage amplitude in an AC circuit with a capacitor?

What occurs to the charge on a capacitor as the AC source frequency increases?

In terms of energy storage, what is the primary role of a capacitor in an AC circuit?

Which equation accurately represents the current in a capacitor connected to an AC source?

If a capacitor is charged with a DC source and is then disconnected, can it store charge indefinitely in isolation?

What is the relationship between the frequency and the capacitive reactance in an AC circuit?

An AC circuit shows a phase shift between current and voltage. What does a positive phase shift indicate in a capacitive circuit?

Consider an RC circuit where a capacitor is charged and then connected to a resistor. What determines the time constant of this circuit?

When analyzing an AC circuit with capacitors, what is a common misconception?

What is the primary function of a transformer?

In a step-up transformer, the secondary coil has:

What is the relationship between primary and secondary voltages in an ideal transformer?

What is an ideal transformer?

If the primary coil of a transformer has 300 turns and the secondary coil has 150 turns, what type of transformer is it?

Which of the following factors does NOT affect the efficiency of a real transformer?

What is the back emf in the primary coil of a transformer associated with?

If a transformer has an efficiency of 90%, and the input power is 1000 W, what is the maximum output power?

What happens to the current in a step-up transformer?

Eddy currents in a transformer are reduced by which method?

During the operation of a transformer, why is there a phase difference between primary and secondary currents?

What type of magnetic core is typically used to reduce energy losses in transformers?

Which of the following is NOT a physical principle utilized in the operation of transformers?

If a transformer has primary and secondary turns in the ratio 1:2, and the primary voltage is 120 V, what is the secondary voltage?

In an ideal transformer, the power input is equal to what?

What is the relationship between the peak voltage and the root mean square (RMS) voltage in an AC circuit?

In a series LCR circuit, how does the phase difference change when the frequency of the AC source increases?

In a series LCR circuit, which component causes a lead in phase with respect to the voltage applied?

What happens to the current in a series LCR circuit at resonance?

What is the value of the impedance Z in a series LCR circuit when the angular frequency is equal to the resonant frequency?

Which of the following relationships is used to express the total impedance in a series LCR circuit?

How does increasing the resistance R in a series LCR circuit affect the quality factor Q?

At what condition does maximum power transfer occur in a series LCR circuit?

What type of waveform does the current produce in a purely inductive circuit?

If the frequency of the AC source in a series LCR circuit is tripled, what happens to the capacitive reactance?

Which phasor represents the voltage across the resistor in a series LCR circuit?

What effect does increasing inductance have on the behavior of a series LCR circuit at a fixed frequency?

Which of the following statements about an LCR circuit at resonance is correct?

How does the phase angle φ between voltage and current behave when the circuit is capacitive?

What is the effect of halving the capacitor's capacitance in a series LCR circuit?

If two series LCR circuits have the same resistance but different inductances, how will their resonant frequencies compare?