Description : Why is the ac induction motor used more often than other types?
Last Answer : They are simple and inexpensive to make.
Description : What is the most widely used combination-bias system?
Last Answer : The voltage-divider type.
Description : How many systems dealing with accounting applications have been widely accepted?
Last Answer : Six.
Description : Why is the Gramme-ring armature not more widely used
Last Answer : Only outside of coils cut flux (inefficient).
Description : What are the four widely used variations of the NRZ encoding method?
Last Answer : a. Non-return-to-zero level (NRZ-L). b. Enhanced non-return-to-zero level (E-NRZ-L). c. Non-return-to-zero mark (NRZ-M). d. Non-return-to-zero space (NRZ-S).
Description : Which of the eight methods for encoding digital data onto magnetic tape is most widely used because it’s accurate, simple, and reliable?
Last Answer : Non-return-to-zero (NRZ) encoding.
Description : What two features make the Huntron Tracker 2000 a widely used troubleshooting tool?
Last Answer : It eliminates the need for multiple pieces of test equipment and it is lightweight and portable
Description : __________ steel is widely used for the manufacture of motor car crankshafts. (A) Silicon (B) Nickel (C) Chrome (D) High speed
Last Answer : (C) Chrome
Description : 'GASOHOL' widely used in Brazil as a motor fuel is a mixture of alcohol and (A) Petrol (B) LPG (C) Light hydrocarbon gases (e.g. butane or propane) (D) None of these
Last Answer : (A) Petrol
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 : What leads in a simple synchro system are connected to the ac power line?
Last Answer : The rotor leads.
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 : Most shipboard distribution systems use ac power that has what number of phases?
Last Answer : Three.
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 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 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 true power in an ac circuit?
Last Answer : True power is the power dissipated in the resistance of the circuit or the power actually used in the circuit.
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 : 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 : 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 : What determines the phase relationship between the voltages in a two-phase ac generator?
Last Answer : Placement of armature coils.
Description : What are the three basic types of ac motors?
Last Answer : Series, synchronous, induction.
Description : Which type of AC single-phase motor will also operate on direct current? A. Split-phase B. Series-wound C. Shaded-pole D. Repulsion-start
Last Answer : Answer: B
Description : The most common type of ac motor is the: A. single-phase induction motor B. two-phase induction motor C. three-phase induction motor D. two-phase squirrel -cage motor
Last Answer : The most common type of ac motor is the: three-phase induction motor
Description : What are the two functions of the servo motor in the system
Last Answer : To move the load and provide feedback data to the error detector.
Description : How do dual-motor dual capstan drives maintain a constant tape tension while operating in either a forward or reverse direction?
Last Answer : Each capstan is driven by its own motor. It maintains tape tension by slowing down one of the motors. When the tape motion is reversed, the opposite motor is slowed down.
Description : What are two advantages of a two-motor reeling system over a take-up control reeling system?
Last Answer : The two-motor configuration runs in both directions and a holdback voltage helps control tape tension, but it does not properly control tape tension during starts and stops.
Description : In the actuator arm assembly of a hard disk drive transport, what device can position the magnetic heads to the correct track of a hard disk more accurately than a dc stepper motor?
Last Answer : Voice coil servo.
Description : What part of a floppy disk drive transport uses a dc stepper motor to position the magnetic heads over the recording surface of a floppy disk?
Last Answer : Actuator arm assembly.
Description : The drive motor of a 3-1/2", 1.44-MB floppy disk drive spins the disk at what RPM?
Last Answer : 600 RPM.
Description : Armature reaction in a dc motor causes a shift of the neutral plane in which direction?
Last Answer : Opposite the rotation.