Capacitor and AC Circuit Principles

<p>They are exactly opposite. (A)</p> Signup and view all the answers

<p>The time it takes for the charged current to decay. (D)</p> Signup and view all the answers

<p>Position B (C)</p> Signup and view all the answers

<p>No EMF is generated. (C)</p> Signup and view all the answers

<p>To maintain a constant current direction in the circuit. (C)</p> Signup and view all the answers

<p>Position A (B)</p> Signup and view all the answers

<p>They switch contact to ensure consistent current flow. (C)</p> Signup and view all the answers

<p>Transformation of AC voltage into DC voltage. (C)</p> Signup and view all the answers

<p>High current flow due to short circuits. (D)</p> Signup and view all the answers

<p>It alternates but is redirected by the commutator. (D)</p> Signup and view all the answers

<p>To prevent displacement by centrifugal force (D)</p> Signup and view all the answers

<p>By employing screening and suppression techniques (A)</p> Signup and view all the answers

<p>To maintain insulation resistance in various conditions (B)</p> Signup and view all the answers

<p>Silver brazing (D)</p> Signup and view all the answers

<p>A splined drive shaft (A)</p> Signup and view all the answers

<p>To secure the brushes and limit wear (C)</p> Signup and view all the answers

<p>Spade or plate type terminals (D)</p> Signup and view all the answers

<p>To reduce eddy current losses and enhance magnetic flux (A)</p> Signup and view all the answers

<p>They can be less than the instantaneous voltage and current values. (C)</p> Signup and view all the answers

<p>Average power is half of the maximum positive power value. (B)</p> Signup and view all the answers

<p>They are in phase and pass through zero at the same time. (A)</p> Signup and view all the answers

<p>4.0 W (A)</p> Signup and view all the answers

<p>To provide initial torque for starting (B)</p> Signup and view all the answers

<p>Shunt field winding (A)</p> Signup and view all the answers

<p>A value less than either of the original numbers. (B)</p> Signup and view all the answers

<p>The average value of power. (B)</p> Signup and view all the answers

<p>Shunt, compensating, and commutating windings (B)</p> Signup and view all the answers

<p>24Vdc and 1500amperes (D)</p> Signup and view all the answers

<p>Inductive reactance increases with lower frequency voltages. (A)</p> Signup and view all the answers

<p>It calculates the average power consumed in the circuit. (C)</p> Signup and view all the answers

<p>The voltage and current vary sinusoidally (B)</p> Signup and view all the answers

<p>To ensure sparkless commutation from no load to full load (D)</p> Signup and view all the answers

<p>Alternating current (AC) (A)</p> Signup and view all the answers

<p>Series winding (C)</p> Signup and view all the answers

<p>It is 0.707 times the peak value. (C)</p> Signup and view all the answers

<p>It is 0.637 times the maximum value. (A)</p> Signup and view all the answers

<p>They respond to average values but are calibrated to read RMS. (A)</p> Signup and view all the answers

<p>Triangular waveforms are used primarily as electronic signals. (C)</p> Signup and view all the answers

<p>I RMS equals I PEAK divided by 0.707. (A)</p> Signup and view all the answers

<p>When the waveform is entirely linear. (C)</p> Signup and view all the answers

<p>Different AC waveforms can have varying shapes. (A)</p> Signup and view all the answers

<p>It raises the temperature by 70.7°C. (A)</p> Signup and view all the answers

The process of converting alternating current (AC) to direct current (DC) by reversing the current direction in each cycle.

A device that reverses the direction of current flow in a loop, ensuring a unidirectional current in the external circuit.

The point in the generator's rotation where the loop is not cutting any magnetic field lines, resulting in zero induced electromotive force (EMF).

The point in the generator's rotation where the loop cuts the maximum number of magnetic field lines, generating the highest induced EMF.

A short circuit occurs when the brushes contact both segments of the commutator simultaneously, resulting in a high current flow.

The process by which the commutator switches the contacts between the brushes and the coils, ensuring that current always flows in the same direction in the external circuit.

The principle that the induced EMF in a conductor is proportional to the rate of change of magnetic flux through the conductor.

A device that converts mechanical energy into electrical energy by using a rotating loop in a magnetic field.

A type of electric generator designed to both start a motor and generate electricity.

A heavy winding connected in series with the armature in a starter generator.

A winding connected in parallel with the armature, providing a constant field for operation as a generator.

A winding that improves commutation by creating a magnetic field that cancels out armature reaction.

Special windings on the poles of a DC machine that generate a magnetic field to counteract armature reaction and provide smooth commutation.

A hollow shaft with splines to fit a drive shaft, ensuring the armature rotates. This allows power transfer from the drive shaft to the generator.

Made up of steel laminations, forms the heart of the armature, and provides a secure base for armature windings.

Groups of copper windings that create the magnetic field in the generator. They are carefully placed in slots within the armature core.

Thin strips of copper, they connect to the armature windings and slide against the commutator segments, transmitting the generated current to the external circuit.

Flexible copper braid, attached to the brushes, extending to terminals, enabling connectivity to the generator's main terminals.

The process of ensuring that no sparking occurs at the brushes. This is vital to prevent interference with radio signals.

A method to shield the generator from interfering with radio signals. It involves enclosing the generator in a metallic enclosure to prevent radio waves from escaping.

A method used to determine the effective value of an alternating current (AC) by considering its heating effect. It represents the equivalent DC current that would produce the same amount of heat in a resistor.

The measure of the maximum value of an alternating current (AC) or voltage wave.

The average value of an alternating current (AC) is calculated by averaging all the instantaneous values over half a cycle.

A type of AC waveform where the voltage or current stays at a constant level for a period of time, then abruptly changes to another constant level, and repeats this cycle.

A type of AC waveform that rises and falls linearly in a triangular shape.

The relationship between RMS and average values is important for understanding how AC is measured and used in practical applications. For a DC waveform, the average value is the same as the maximum value.

The most common type of AC waveform, characterized by a smooth, sinusoidal shape.

Different types of AC waveforms are used in electronics, each with specific characteristics and applications.

In a resistive AC circuit, the voltage and current waves are in phase, meaning they reach their maximum and minimum values at the same time, and they pass through zero at the same time going in the same direction.

The average power in a resistive AC circuit is equal to half of the maximum positive power value.

The instantaneous power in a resistive AC circuit is calculated by multiplying the instantaneous voltage and current values at any point in time.

The power wave in a resistive AC circuit has a frequency twice that of the voltage and current waves.

Inductive reactance (XL) is the opposition to current flow offered by an inductor in an AC circuit. It increases with increasing frequency.

Inductive reactance is directly proportional to the frequency (f) of the AC voltage and the inductance (L) of the inductor.

A low frequency AC voltage allows more time for the current to rise through an inductor, resulting in higher current flow compared to a high frequency voltage.

The relationship between inductive reactance (XL), frequency (f), and inductance (L) is represented by the formula: XL = 2πfL.

The time constant of a capacitive circuit is a measure of how quickly a capacitor charges or discharges. It is directly proportional to the capacitance and the resistance of the circuit.

Capacitive reactance (Xc) is the opposition to current flow in an AC circuit due to a capacitor. The higher the reactance, the more the capacitor resists current flow.

Capacitive reactance is inversely proportional to capacitance. This means that as capacitance increases, capacitive reactance decreases, allowing more current to flow.

Increasing frequency in an AC circuit reduces capacitive reactance. This is because the capacitor charges and discharges more quickly with higher frequencies, allowing more current to flow.

The phase relationship between current and voltage in an AC capacitive circuit is opposite to that of an inductive circuit. Voltage lags behind current by 90 degrees.