ELEX Q AND A part 1

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If bandwidth increases, the

Q decreases

the dc output of a bridge type circuit is__ that of equivalent center tapped circuit.

more than

Which of the following robot drive mechanism is the cheapest to buy but has a limited payload?

pneumatic

The output of an OR gate will be low if

all inputs are LOW

If a 175-V dc source were connected in series with the utility mains from a standard wall outlet, the result would be

fluctuating dc

In constructing transformers, the primary and secondary windings should have

tight magnetic coupling

If a sine wave voltage varies from 0-200 V, how much is its instant voltage at 90 degrees?

200 V

What is the typical slew rate of Fairchild 741 op-amp?

0.5 V/us

Small microcomputer used as a dedicated controller for a machine, a piece of equipment, or a process.

Microcontroller

Where do you classify cobalt as material?

Ferromagnetic

If the base-emitter junction is open, the collector voltage is

Vcc

The absolute maximum rating for op-amps interval power dissipation is

500mW

The power dissipated in the core due to hysteresis and eddy current losses

iron loss

Which of the following is not an internal digital IC fault?

poor solder connections

A diode limiter circuit

can cause objectionable signal distortion

An elementary generator consists of a single coil rotating in a magnetic field. Why is no voltage induced in the coil as it passes through the neutral plane?

Flux lines are not being cut

A manufacturer quotes in his specifications that a silicon diode conducts 50 mA at 1 V. Determines its bulk resistance.

6 ohms

A radio equipment will be used to 70% at 50 amperes rating fo 5 hours, how much capacity of dry battery is needed?

175

Type of feedback employed in oscillators

positive

A digital circuit that oscillates between two unstable output states.

astable multivibrator

Capacitors are used to store data in

none of the above

The input resistance of a common-base amplifier is

very low

What is the normal resting state of the SET and CLEAR inputs in a NAND gate latch?

SET=1, CLEAR=1

Voltage that is present at the output of an operational amplifier with its two inputs grounded.

output offset voltage

Type of waveform generated by the sweep generator of the CRT

sawtooth

What are the primary methods of controlling electrical power?

all of the above

Class of programmable logic devices wherein its AND array is programmable while its OR array is hard wired.

PAL

Flux linkage equals

flux times number of turns

The device used to use for rectifying a weak ac signal is a

Back Diode

How many NAND-gates are required to form an OR-gate?

What gain is significant when an op-amp is used as a voltage comparator?

open-loop gain

Process of repairing the ruptured crystal structure caused by ion implantation by heating.

annealing

Suppose a purely resistive impedance of 75 Ω must be matched to a purely resistive impedance of 300 Ω. A quarter-wave section would need to have

Zo=150 Ω

How many cells would a 16 word x 6 bit memory contain?

Find the half-power bandwidth of a parallel resonant circuit which has a resonant frequency of 8.1 MHz and Q of 150.

54 kHz

The purpose of the I layer in a PIN diode is to

minimize the diode capacitance

The typical saturation flux density for most magnetic materials.

2 Wb/m2

_____ is a measure of consistency of measurements.

precision

A digital computer used for the automation of industrial processes, such as control of machinery or factory assembly lines

PLC

A JFET always operates with

the gate-to-source pn junction reverse-biased

If Ic is 50 times greater than IB, then βDC is

What is the ripple frequency of a half-wave rectifier with an input line frequency of 60 Hz?

60 Hz

Which of the following amplifiers is considered linear?

either class A or B

Electrical classification of materials having 8 electrons.

insulator

A full 360 deg sine wave signal is applied to an unknown class of amplifier. If the output delivers only a pulse of less than 180 deg, what class does this amplifier belongs?

class C

Which of the following is not a general characteristic of an ac wave?

the electrons always flow in the same direction

A summing amplifier can have

Two or more input signals

In an NPN circuit, the collector

is positive with respect to the emitter

The bandwidth of a multistage amplifier is ___ that of a single stage amplifier.

less than

A device used to mechanically measure the output power of a motor

dynamometer

How many major lobes are produced by a paraboloid reflector?

one

The main problem with a bar-graph meter is that:

it can’t give a very precise reading

What is the maximum efficiency of a full-wave center-tapped rectifier?

81.2%

Which of the following is false, concerning air cores versus ferromagnetic cores?

air concentrates the magnetic lines of flux

Which statement is wrong regarding μA741 when its supply voltage is increased?

large variation in the input offset voltage

If a power supplies 30 V with no load and 20V under full load, what is the percentage regulation?If a power supplies 30 V with no load and 20V under full load, what is the percentage regulation?

50%

Which type of the following oscillator types uses transformer coupling to feed back a portion of the signal voltage. It is sometimes called a “tickler” coil.

Armstrong circuit

A pulsating dc applied to power amplifiers causes

hum in the circuit

In a linear op-amp circuit, the

Op-amp does not go into saturation

Situation when a circuit’s output level for a given set of input conditions can be assigned as either a 1 or 0.

don’t care

The regulator with the highest efficiency is the

switching regulator

When a closed-loop system is used to maintain physical position it is referred to as

servo system

An integrated circuit for both astable and monostable applications

555 timer

Result obtained when a 1 is added to the least significant bit position of a binary number in the 1’s-complement form

2’s complement

Low sensitive DC voltmeter provides inaccurate result when measuring ____ circuits.

high resistance

Simple current limiting produces too much heat in

Pass transistor

When an armature opens in dc motor, it may cause

intermittent sparking

.Suppose you have an unlimited supply of 1-W, 1000-Ω resistors, and you need a 500-Ω resistance rated at 7 W or more. This can be done by assembling

four sets of two resistors in series, and connecting these four sets in parallel

A significant advantage, in some situations, of a toroidal coil over a solenoid is the fact that

the magnetic flux in a toroid is practically all within the core

The input offset current is usually

less than the input bias current

Combination of ac motor, dc generator, and exciter to provide adjustable voltage dc power to a dc motor.

ward-leonard system

The ideal internal resistance of an emitter should be

zero

A frequency synthesizer has

exceptional stability

The approximation with a maximally flat passband is

Inverse chebyshev

Electron flow assumes charges flow from

negative to positive

The closed-loop voltage gain of an inverting amplifier equals

The feedback resistance divided by the input impedance

A bubble memory is best suited for:

a large computer

The operating frequency of a Wien-bridge oscillator is given by ___.

1/2piRC

In an LC oscillator, if the value of L is increased four times, then frequency of oscillations is ____.

decreased two times

This type of electrical machine is used for varying the input voltage into a higher or lower potential without changing the power transferred.

transformer

Amplifier of low-level signals that provides an output that is an accurate multiple of the difference between two input signals

instrumentation amplifiers

Which of the following is not a characteristic of CMOS chips?

ability to handle extremely high power

How are the networks able to transform one impedance to another?

Resistance in the networks substitute for the resistances in the load.

Power source that converts desired electricity to the other.

motor set

It is a robot structure wherein the body can pivot vertically and horizontally and that arms move radially

polar structure

How do you determine if diode is effective?

diode resistance is either very high or very low in either direction

The energy of an oscillator can be sourced by

capacitance of inductive coupling from the tuned circuit

Air works well as a dielectric mainly because it

has low loss

An AC bridge that measures inductance in terms of resistance and capacitance.

Owen’s bridge

A monopulse receiver has how many separate channels?

three

A meter when ___ damped will become insensitive to small signals.

overdamped

In a linear regulator, the control transistor is conducting

all of the time

Each stage of a four-stage amplifier has a voltage gain of 15. The overall voltage gain is

50,625

With respect to memory, which of the following terms means that the data contents vanish if power is removed from a chip?

volatility

What is the purpose of the emitter capacitor?

to avoid drop in gain

The number of digits used by a number system.

radix

A Schmitt trigger is used to provide

A short duration pulse

One of the following items below is not one of the main components of an alternating current power supply.

Rectifier

What are the two basic categories of industrial robots?

pick and place manipulator and intelligent robot

100

What direction is the magnetic field about a conductor when current is flowing?

in a direction determined by the left hand rule

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