Description : What is the reactive power in an ac circuit?
Last Answer : Reactive power is the power returned to the source by the reactive components of the circuit.
Description : What is the difference between calculating impedance in a series ac circuit and in a parallel ac circuit?
Last Answer : In a series circuit impedance is calculated from the values of resistance and reactance. In a parallel circuit, the values of resistive current and reactive current must be used to calculate total impedance.
Description : What is the value of Z in a series ac circuit where XL = 6ohms, XC = 3ohms, and R = 4ohms?
Last Answer : X = XL – XC or X = XC - XL
Description : What term is given to total opposition to ac in a circuit?
Last Answer : Impedance
Description : If the permeability of the core of a coil increases, what happens to (a) inductance and (b) true power in the circuit?
Last Answer : (a) Inductance increases; (b) true power decreases.
Description : If inductance increases in a series LR circuit, what happens to true power?
Last Answer : It decreases.
Description : What leads in a simple synchro system are connected to the ac power line?
Last Answer : The rotor leads.
Description : Most shipboard distribution systems use ac power that has what number of phases?
Last Answer : Three.
Description : Ships’ generators produce 450-volt, three-phase, ac power; however, most equipment uses 117-volt, single-phase power What transformers and connections are used to convert 450- volt, threephase power to 117-volt, single-phase power?
Last Answer : A method of generating oscillations, a method of turning the oscillations on and off (keying), and an antenna to radiate the energy.
Description : Which of the following statements is true concerning a stepdown transformer in an operating AC power circuit? A. Voltage and current will both be increased. B. Voltage and current will both be decreased C. Voltage decreases as current increases. D. Voltage increases as current decreases.
Last Answer : Answer: C
Description : Which of the following statements concerning AC circuits is correct? A. The power factor of a resistive circuit is always zero. B. True power in an inductive circuit always equals apparent power. ... . D. Total opposition to the flow of alternating current depends upon the amount of reactive power.
Description : If an ac voltmeter is connected between the S2 and S3 windings on a TX, at what two rotor positions should the voltmeter read maximum voltage?
Last Answer : . 150º and 330º
Description : When used for ac current control, during which alternation of the ac cycle does the TRIAC control current flow?
Last Answer : During both alternations.
Description : What is the basic difference between the primaries of ac and dc rate generators?
Last Answer : The method of primary excitation (ac and permanent magnet).
Description : In the output of an ac error detector, what indicates the (a) direction and (b) amount of control necessary for correspondence?
Last Answer : (a) Phase. (b) Amplitude.
Description : What are the electrons called that give up energy to the ac field in a magnetron?
Last Answer : Working electrons.
Description : Why does using ac vice dc bias voltage result in a stronger output signal?
Last Answer : Because an ac bias voltage of the proper frequency and level places the input signal away from both steps in the magnetism curve. The result is two undistorted output signals that are combined into one strong output.
Description : What are three advantages of adding an ac bias voltage to the input signal instead of adding a fixed dc bias voltage?
Last Answer : a. Reproduces a stronger output signal. b. Greatly improves the SNR. c. Greatly reduces the natural tape hiss.
Description : Why does adding dc vice ac bias voltage to the input signal result in a poor signal-to-noise ratio (SNR)?
Last Answer : With dc bias, the SNR is poor because only a small portion of the magnetism curve is straight enough to use, thus the output signal is weak compared with the natural tape hiss.
Description : rid-leak biasing in effect rectifies the input ac signal. What feature
Last Answer : Unequal charge and discharge paths of the coupling capacitor Cc.
Description : If the mu of a tube is 85 and the signal at the control grid is 4 volts ac, the plate voltage will vary by what amount?
Last Answer : 340 volts.
Description : The plate voltage of a tube will vary 126 volts when a 3-volt ac signal is applied to the control grid. What is the gain of this tube?
Last Answer : 42.
Description : An ac voltage is applied across a diode. The tube will conduct when
Last Answer : Positive.
Description : What is the term for the opposition that a capacitor presents to ac?
Last Answer : Capacitive reactance.
Description : What is the term for the opposition an inductor presents to ac?
Last Answer : Inductive reactance.
Description : What component causes a generator to produce dc voltage rather than ac voltage at its output terminals?
Last Answer : A commutator
Description : Why should you avoid using ac-powered test equipment when wearing a wrist strap?
Last Answer : For your own safety.
Description : Why is the dc scale on a multimeter different than the ac scale?
Last Answer : The meter movement reacts to average ac voltage and current and the effective value is desired.
Description : List three meter movements that can measure either ac or dc without the use of a rectifier.
Last Answer : Electrodynamic, moving vane, and hot-wire or thermocouple.
Description : What value is indicated on the scale of an ac meter?
Last Answer : Effective value (rms).
Description : What value does a meter movement react to (actually measure) when measuring ac?
Last Answer : Average value.
Description : How can a d’Arsonval meter movement be adapted for use as an ac meter?
Last Answer : By the use of a rectifier
Description : The frequency response of test equipment refers to what aspect of ac voltage measurements?
Last Answer : the range of frequencies that can accurately be measured.
Description : What determines the phase relationship between the voltages in a two-phase ac generator?
Last Answer : Placement of armature coils.
Description : What type of ac motor is most widely used?
Last Answer : Single-phase induction motor.
Description : Why is the ac induction motor used more often than other types?
Last Answer : They are simple and inexpensive to make.
Description : What are the three basic types of ac motors?
Last Answer : Series, synchronous, induction.
Description : What tool is used to de-energize capacitors in a circuit that has been disconnected from its power source?
Last Answer : Shorting probe.
Description : What is the power factor of a circuit?
Last Answer : Power Factor is a number representing the portion of apparent power actually dissipated in a circuit.
Description : Refer to figure 3-55(A). If the following resistors were replaced with the values indicated: R1 = 900Ω, R3 = 1kΩ, what is the total power in the circuit? What is ER2?
Last Answer : PT = 60 W, ER2 = 10 V.
Description : A series circuit consists of two resistors in series. R1 = 25 ohms and R2 = 30 ohms. The circuit current is 6 amps. What is the (a) source voltage, (b) voltage dropped by each resistor, (c) total power, and (d) power used by each resistor?
Last Answer : (a) 330 volts. (b) E1 = 150 volts. E2 = 180 volts. (c) 1.98 kilowatts. (d) P1 = 900 watts. P2 = 1.08 kilowatts component but in a parallel circuit total current divides among the available paths.
Description : What is the power used in a circuit that has 10 amperes of current through a 10-ohm resistor?
Last Answer : 1 kilowatt.
Description : What is the current in a circuit with 5 ohms of resistance that uses 180 watts of power?
Last Answer : 6 amperes.
Description : . If the power distribution system shown in figure 2-22 uses selective tripping, what is the time delay rating for each of the circuit breakers shown?
Last Answer : CB1-long time delay; CB2, CB3-short time delay; CB4 through
Description : For what class of operation is the final rf power amplifier of a plate-modulator circuit biased?
Last Answer : Class C
Description : What impedance relationship between the output of one circuit and the input of another circuit will provide the maximum power transfer?
Last Answer : Equal impedance.
Description : Which of the following is not true: A) An oscillator is a circuit that converts DC to AC B) An oscillator is an amplifier that supplies its own input signal C) All oscillators generate sine waves D) In phase feedback is called positive Feedback
Last Answer : C) All oscillators generate sine waves
Description : In a simple dc circuit, voltage equals resistance multiplied by current. This is also considered true in an AC circuit if the what values of the current and voltage are used.
Last Answer : ANSWER: ROOT MEAN SQUARE (RMS) VALUES
Description : How many types of power in AC circuit ?
Last Answer : Three types of power in AC circuit. Namely , 1) actual power , 2) reactive power , 3) apparent power.
Description : An AC circuit consists of a resistance and a choke coil in series . The resistance is of 220 `Omega` and choke coils is of 0.7 H . The power abosorbed
Last Answer : An AC circuit consists of a resistance and a choke coil in series . The resistance is of 220 ` ... 50 Hz , source connected with the circuit , is