Description : Heat sinks are frequently used with _____________. A. power transistors B. vacuum tubes C. tunnel rectifier diodes D. all of the above
Last Answer : Answer: A
Description : A faulty 'function generator' shown in the illustration may prevent _____________. EL-0095 A. proper pitch control from both the 'bridge' and 'engine room thrust levers' B. the 'split potentiometer ... control pitch C. the pitch meter from indicating accurately D. relays #2 and/or #3 from energizing
Description : The main difference between an electron tube and a transistor is the _____________. A. type of function they can perform B. reaction of electron flow through a gas or vacuum in a transistor C. ... when placed in a tube D. reaction of electron flow through a semiconductor used to form a transistor
Last Answer : Answer: D
Description : RC time constant characteristics, as shown in the illustration, are important in _____________. EL-0086 A. bridge rectifiers for alternator excitation B. timing and pulse shaping circuits C. transistor power amplifier biasing D. motor controller overload protection
Last Answer : Answer: B
Description : Germanium diodes are used in AM detectors because ___
Last Answer : they minimize distortion from nonlinearit
Description : Pure semiconductors silicon and germanium are a) Extrinsic b) Intrinsic c) Insulator d) Diodes
Last Answer : b) Intrinsic
Description : Silicon diodes designed for a specific reverse breakdown voltage, become useful as an electronic power supply voltage regulator, called _____________. A. tunnel diodes B. hot-carrier diodes C. compensating diodes D. Zener diodes
Description : Which of the listed pairs of materials make the best insulators? A. dry air and a vacuum B. tin and lead C. doped silicon and germanium D. paper and oil
Description : Which of the listed pairs of materials make the best insulators? A. copper and aluminum B. glass and mica C. dry air and a vacuum D. doped silicon and germanium
Description : The illustrated circuit is a _____________. EL-0024 A. megohm meter B. Gauss meter C. wheatstone bridge D. germanium diode tester
Last Answer : Answer: C
Description : The potentiometers shown in the illustration are supplied with both (+) and (-) voltages as well as a reference to ground ________________. EL-0095 A. so there is always a spare power ... , the other for relay operation and the potentiometers are in positions where they can be accidentally touched
Description : When Arsenic atoms are added Germanium lattice, it becomes a/an - (1) Insulator (2) Superconductor (3) Intrinsic semiconductor (4) Extrinsic semiconductor
Last Answer : (4) Extrinsic semiconductor Explanation: When a peritavalent (donor) impurity, like arsenic, is added to germanium, it will form covalent bonds with thegermanium atoms, leaving 1 electron relatively ... this manner - either with Nor P-type impurities - are referred to as EXTRINSIC semiconductors.
Description : An example of semiconductor is - (1) German silver (2) Germanium (3) Phosphorous (4) Arsenic
Last Answer : (2) Germanium Explanation: Purified germanium is a semiconductor, with appearance most similar to elemental silicon. Like silicon, germanium naturally reacts and forms complexes with oxygen in nature. Unlike silicon, it is too reactive to be found naturally on Earth in the free (native) state.
Description : Give reason: Silicon is used widely even through Germanium is a better semiconductor material.
Last Answer : Silicon is the second most abundantly available material and it can be used at higher temperature. Hence it widely used than Germanium.
Description : Semiconductor germanium and silicon are (a) Pentavalent (b) trivalent (c) divalent (d) tetravalent
Last Answer : (d) tetravalent
Description : When Arsenic atoms are added to Germanium lattice, it becomes a/an (1) Insulator (2) Superconductor (3) Intrinsic semiconductor (4) Extrinsic semiconductor
Last Answer : Extrinsic semiconductor
Description : An example of semiconductor is (1) German silver (2) Germanium (3) Phosphorous (4) Arsenic
Last Answer : Germanium
Description : Considering the function of the circuit shown in the illustration, what is the purpose of supplying the thrust lever potentiometers with both (+) and (-) 15 volts? EL-0095 A. To select which ... alternate voltage supply if the other fails. D. So as to automatically select the position of Relay #
Description : Define semiconductor diodes.
Last Answer : It is a device in which electric current can flow in one direction. It has 2 terminals P and N.
Description : A semiconductor is a material with a _____________. A. conductivity higher than a normal conductor B. conductivity higher than a normal insulator C. high conductivity at low temperatures D. low conductivity at high temperatures
Description : On AC vessels, which of the following statements represents the most difficult problem involved in obtaining a DC potential suitable for use by computer components? A. A stepdown transformer is ... voltage must be rectified and made ripple free. D. Rectifiers cannot operate with voltage regulators.
Description : What is rectifier? Write few types of rectifiers.
Last Answer : Rectifier is a device which converts AC supply into DC. Following are the types of rectifiers generally used. a. Copper oxide rectifier. b. Selenium rectifier. c. Electrolytic rectifier. d. Mercury arc rectifier. e. Tungar rectifier.
Description : Vacuum tubes have been replaced by-----? A. Conductors B. Diodes C. Transistors (Answer) D. None of these
Last Answer : C. Transistors (Answer)
Description : A semiconductor that decreases in resistance with an increase in temperature is known as a _____________. A. resistor B. thermistor C. diode D. thermopile
Description : Tunnel diode is a: a) Power diode b) Has light doping c) Has heavy doping d) Is a reverse recovery diode Ans: C 76.LEDs are fabricated from: a) Silicon b) Germanium c) Si or Ge d) Gallium arsenide
Last Answer : Ans: D
Description : The use of four diodes, in a full-wave bridge rectifier circuit, will __________. A. provide unidirectional current to the load B. allow a very high leakage current from the load C. convert direct current to alternating current D. offer high opposition to current in two directions
Description : Which semiconductor sources (LD or LED) emit more focused light and are capable of launching sufficient optical power into both single mode and multimode fibers?
Last Answer : LDs.
Description : Shunt, series, and compound wound motors, are all DC motors designed to operate from _____________. A. constant potential, variable current DC sources B. variable potential, constant current DC ... C. variable potential, variable current DC sources D. constant potential, constant current DC sources
Description : Write the specifications of linear and non- linear potentiometers. State its applications
Last Answer : Specifications of linear & nonlinear potentiometers: 1. Ohmic range: 10Ω to 125 kΩ 2. Power rating : 100watt to 200 watt 3. Tolerance : 2% 4. Voltage Rating: 5V-500V 5. Operating ... 7. Used as potential dividers. 8. It is used for panel control in receivers, function generator etc
Description : Standardization of potentiometers is done so that (A) They become accurate and direct-reading. (B) They become accurate and precise. (C) They become accurate and take zero current when null condition is reached. (D) Power consumption is reduced during operation.
Last Answer : Standardization of potentiometers is done so that They become accurate and direct-reading.
Description : Rectifiers are used to convert - (1) Direct current to Alternating current (2) Alternating current to Direct current (3) high voltage to low voltage (4) low voltage to high voltage
Last Answer : (2) Alternating current to Direct current Explanation: Converting DC power from one voltage to another is much more complicated. One method of DC-to-DC conversion first converts power to AC (using a ... inverter), then uses a transformer to change the voltage, and finally rectifies power back to DC.
Description : C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator where as Si is intrinsic semiconductor. This is because (1) The four bonding electrons in the case of C ... the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Last Answer : (4) The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Description : In the illustrated circuit, if the input to leads 'B' and 'Y' was 24 VDC the output between 'A' and 'X' will be _________. EL-0069 A. 24 VDC B. 22.8 VDC, 24 VDC minus the 1.2 VDC voltage drop across two diodes C. undeterminable without knowing the turns ratio of the transformer D. 0 VDC
Description : Routine maintenance of a ship's service alternator should include ______________. A. changing the pedestal bearing insulation yearly B. megger testing of all rectifying diodes C. lubricating excitation slip rings D. periodic cleaning of the air filters or screens
Description : Which of the devices listed is indicated by the symbols lettered 'A' to 'F', shown in the illustration? EL-0016 A. Diodes B. Linear inductors C. Capacitors D. Transistors
Description : What types of inverters require feedback diodes?
Last Answer : VSI with RL load.
Description : Why diodes should be connected in antiparallel with the thyristors in inverter circuits?
Last Answer : For RL loads, load current will not be in phase with load voltage and the diodes connected in antiparallel will allow the current to flow when the main thyristors are turned off. These diodes are called feedback diodes.
Description : What are the advantages of freewheeling diodes in a controlled in a controlled rectifier?
Last Answer : a. Input power factor is improved. b. Load current waveform is improved and thus the load performance is better.
Description : What is the function of freewheeling diodes in controlled rectifier?
Last Answer : It serves two process. a. It prevents the output voltage from becoming negative. b. The load current is transferred from the main thyristors to the freewheeling diode, thereby allowing all of its thyristors to regain their blocking states.
Description : Which electronic component was made out of semiconductor material? A) Vacuum tubes B) Transistors C) ICs D) All of above
Last Answer : Answer : C
Description : What is the PIV of all type rectifiers?
Last Answer : The PIV of rectifier: - Half wave rectifier=Vm, Center tape wave rectifier=2Vm Bridge full wave=Vm
Description : ECE Board Exam March 1996 A device to be connected across the headset in telephone receivers to reduce the effects of acoustic shock. A. Ground B. Two rectifiers in parallel with opposite polarities C. Protector D. Fuse
Last Answer : B. Two rectifiers in parallel with opposite polarities
Description : A half-wave voltage doubler is made up of how many half wave rectifiers?
Last Answer : Two.
Description : State classification of Phase controlled rectifiers.
Last Answer : Classification of phase controlled rectifiers:
Description : A freewheeling diode in phase -controlled rectifiers (a) enables inverter operation (b) is responsible for additional reactive power (c) improves the line power factor (d) is responsible for additional harmonics
Last Answer : A freewheeling diode in phase -controlled rectifiers improves the line power factor
Description : Electronic Voltmeters which use rectifiers employ negative feedback. This is done - a) To increase the overall gain b) To improve stability c) To overcome non -linearity of the diodes d) None of the above
Last Answer : Electronic Voltmeters which use rectifiers employ negative feedback. This is done - To overcome non -linearity of the diodes
Last Answer : Ac to dc
Description : An open shunt field in a direct current machine may be located by connecting the field circuit to an external power source, equal to the rated field voltage or less, and tested with a voltmeter from ... C. any suitable ground to any available line lead D. any field pole to each field coil lead
Description : If a DC motor runs hot, the cause may be _____________. A. high mica condition B. low ambient temperature C. clogged ventilation ducts D. an open in the shunt field