Rotary comverters and Electronics Flashcards by Evelyn Yap

A rotary converter is a single machine with

1 armature and 1 field

How well did you know this?

Not at all

Perfectly

A synchronous converter can be started

by means of a small auxiliary motor
from AC side as induction motor
from DC side as DC motor

How well did you know this?

Not at all

Perfectly

What is the efficiency of full wave rectifier?

A. 100%
B. 90 %
C. 80%
D. 70%

How well did you know this?

Not at all

Perfectly

An unregulated power supply which consist of a transformer, a rectifier and a filter has some characteristics which are as follows EXCEPT one. Which is it ?

A. it has a good voltage regulation
B. it is relatively inexpensive
C. output voltage depends on input voltage
D. the output voltage varies with the load

How well did you know this?

Not at all

Perfectly

The ripple factor of a power supply is a measure of __

A. its filter efficiency
C. its voltage regulation
B. diode rating
D. purity of power output

How well did you know this?

Not at all

Perfectly

*What is UPS stands for?

A. Uninterrupting Power Supply
B. Uninterruptible Power Supply
C. United Power System
D. Uninterruptible Portable Supply

How well did you know this?

Not at all

Perfectly

An SCR (Silicon Controlled Rectifier) behaves as a ____ switch.

A. bidirectional
C. unidirectional
B. mechanical
D. three-way

How well did you know this?

Not at all

Perfectly

A TRIAC can pass a portion of ___ half-cycle through the load.

A. only positive
B. both positive and negative
C. only negative
D. none of these

How well did you know this?

Not at all

Perfectly

A device that does not have a gate terminal is

A Triac
B. FET
C. SCR
D. Diac

How well did you know this?

Not at all

Perfectly

A device that exhibits negative resistance region is

A. SCR
C. Diac
B. Triac
D. UJT

How well did you know this?

Not at all

Perfectly

A carrier current communication receiver is found where?

A. substation
B. distributor
C. post office
D. radio station

How well did you know this?

Not at all

Perfectly

The Philippines has adopted one of the following primary color television transmission standards. Which one is this?

A. PAL
B. NTSC
C. EUREKA
D. SECAM

How well did you know this?

Not at all

Perfectly

What is the frequency range for TV channels 2 to 13?

A. UHF
C. SHF
B. VHF
D. HF

How well did you know this?

Not at all

Perfectly

Operating frequency in kHz of SW radio station with wavelength of 15 m.

A. 50T
C. 20T
B. 60T
D. 15T

How well did you know this?

Not at all

Perfectly

A type of communication that uses light, rather than electricity to communicate is called

A. Fiber-optic
B. microwave
C. Laser carrier
D. Power-line carrier

How well did you know this?

Not at all

Perfectly

Unit of sound absorption coefficient of materials?

A. Decibel
B. Watts
C. Erg
D. Sabine

dB - sound intensity
w- power
Erg - Energy

How well did you know this?

Not at all

Perfectly

Unit of measure of sound intensity level is ___.

A. Decibel
B. Watts
C. Erg
D. Sabine

How well did you know this?

Not at all

Perfectly

Which of the following is reversible in action?

A. Motor-generator set
C. Rotary converter
B. Motor converters
D. None of these

How well did you know this?

Not at all

Perfectly

When a rotary converter is started by means of a small auxiliary motor, the power of motor must be.

A. Less than the dc output of converter
B. Less than the AC input of the converter
C. Slightly more than the value of friction and windage losses at rated speed
D. Half of de output of converter

How well did you know this?

Not at all

Perfectly

The following are advantages of motor-generator set over rotary converter. EXCEPT:

A. It can be used for power factor correction purposes
B. DC output voltage can be controlled easily by adjusting the field regulator
C. Provided supply voltage
D. It has a comparatively high efficiency

In a 1-phase rotary converter the number of slip rings will be

A. 2
B. 4
C. 1
D. 3

A rotary converter operates at ____ power factor.

A. Low
C. zero
B. High
D. infinite

The turnaround from vacuum tube to solid state dynamic component in 1948 was triggered by the invention of the transistors by the three team men. Which laboratory in U.S. did their work?

A. Westinghouse
C. Bell telephone
B. GE
D. Philips

In reverse PN junction, with the voitage is increasing, the current is _____

A. increasing
C. increasing exponentially
B.decreasing
D. no change

It may be defined as the energy which corresponds to the center of gravity of conduction electrons and holes weighted according to their energies. It is in the middle of forbidden energy gap. A. Valence band B. Conduction band C. Kinetic energy D Fermi level

Which is NOT a semiconductor? A. Selenium B. Silica C. Gallium Arsenide D. Carbon radium

Tubes are preferred to transistors in the following applications EXCEPT one. A. High power B. High Frequency C. High voltage D. Long life

Semiconductor materials have A. metallic B. ionic bond. C. covalent D. mutual

A P-type semiconductor has storage of electron. What charge is it free? A. Intrinsic C. Hole B. Electron D. Proton

Without a dc source, a clipper acts like a ____. A. rectifier B. demodulator C. clamper D. chopper

The primary function of a clamper circuit is to _____. A. suppress variations in signal voltage B. lower negative half-cycle of the signal C. raise positive half-cycle of the signal D. introduce a dc level into an AC signal

The basic reason why a full wave (FW) rectifier has twice the efficiency of a half wave (HW) rectifier is that _____. A. it makes use of transformer B. its ripple factor is much less C. it utilizes both half-cycle of the input D. its output freq. is twice the line freq

What do you call the process electronically drying paint? A. dielectric heating C. induction heating B. convection D. emmisivity

Which stage of a DC power supply uses Zener diode as the main component? A. regulator B. filter C. rectifier D. voltage divider

A live room one whose interior finishing is such that reverberation time of sound is _____ sec. A. 0 B. more than 5 C. less than 1 D. more than 1

Which of the following Logic circuits is the fastest ? A. Resistor-transistor-logic (RTL) B. Transistor-transistor-logic (TTL) C. Variable-threshold-logic (VTL) D. Diode-transistor-logic (DTL)

The gate voltage in a FET at which the drain current Id becomes zero is called A. active voltage B. saturation voltage C.cut-off voltage D. pinch-off voltage

The main factor which differentiates a DE MOSFET from E-only MOSFET is the absence of ; A. insulated gate B. channel C. electrons D. P-N junctions

Piezoelectricity principle is applied in ONE of the following A. ultrasound equipment C. microphones B. thermometer D. TV sets

In 1885, he used a long wire as antenna and develop a practical radio system A. Benjamin Franklin C. Isaac Newton B. Marconi D. Carl Siemen

It refers to a device that merely boosts a signal and passes it on. A. Repeater B. Amplifier C. Booster D. Op-amp

RJ45 is used for A. Data B. Video C. Audio D. CATV

What is the most common fiber optic Cable? A single mode step index B. multi mode step index C. single mode grated index D. multi mode graded index

What is the function of a transducer? A. signal detection B. amplification C. voltage reduction D. energy conversion

How many doped regions does a typical bipolar junction transistor (BJT) have? A one C.three B. two D four

An amplifier with a feedback loop or path for energy to propagate from the output back to the input is A. regenerative feedback B. degenerative feedback C. feedback D. AGC

The depletion region in a junction diode forms what part of a capacitor A. + plate C. dielectric B. - plate D. none of these

Increasing the reverse bias on a varactor diode will cause its capacitance A. decrease C. no change B. increase D. either A or B