Mastery Test 01 - Elec

When an IC has two rows of parallel connecting pins, the device is referred to as a:

CMOS

QFP

DIP

TSSOP

DIP

In microelectronics, a dual in-line package (DIP or DIL), is an electronic component package with a rectangular housing and two parallel rows of electrical connecting pins.

Which of the following statements is true?

A primary cell converts electrical energy into chemical energy

A positive electrode is termed the cathode

The capacity of a cell is measured in volts

Galvanizing iron helps to prevent corrosion

Galvanizing iron helps to prevent corrosion

The purpose of the commutator in a generator or motor is to

change the direction of the current to the stator windings

provide the magnetic field for the motor or generator

change the direction of the current to the rotor as it spins

support the motor or generator shaft

change the direction of the current to the rotor as it spins

When the frequency of the source voltage is increased, the impedance of a parallel RC circuit ____.

cannot be determined

decreases

increases

does not change

decreases

series and parallel RC impedance decreases with increase in frequency

If the flux per pole of a shunt-wound d.c. generator is increased, and all other variables are kept the same, the speed:

Decreases

Stays the same

Increases

None of the choices

decreases

• In case of DC shunt motor, the flux per pole is considered to be constant, torque increases with the increase of load current.

• If the load current increases then the armature current also be increased and the speed slightly falls due to increase in voltage drop in armature.

Which of the following is not a basic Boolean operation?

FOR

OR

AND

NOT

AND

SHOULD BE FOR

Which of the following choices meets the minimum requirement needed to create specialized waveforms that are used in digital control and sequencing circuits?

Basic gates, a clock oscillator, and a De Morgan pulse generator

Basic gates, a clock oscillator, and a Johnson shift counter

Basic gates, a clock oscillator, and a repetitive waveform generator

Basic gates, a clock oscillator, a repetitive waveform generator, and a Johnson shift counter

Basic gates, a clock oscillator, and a repetitive waveform generator

In a photodiode, light produces ___________.

electroluminescence

dark current

reverse current

forward current

reverse current

In normal operation an n-p-n transistor connected in common-base configuration has:

The base at a lower potential than the emitter

The collector at a lower potential at a base

The collector at a lower potential than the emitter

The emitter at a lower potential than the base

The emitter at a lower potential than the base

When checking out a series resistive circuit, you find that the current is higher that it should be. You should look for:

A short

Both a short and a low resistive value

An open circuit

A low resistive value

Both a short and a low resistive value

In a motor, back emf serves to

decrease the flux

increase the power from the field windings

increase the power from the motor

decrease the current in the armature

decrease the current in the armature

The total resistance of the figure below can be found with which of the following formulas?

(R₁ + R₂) || (R₃ + R₄ + R₅)

R₁ + R₂ + R₃ || R₄ || R₅

None of the choices

R₁ || R₂ + R₃ || R₄ || R₅

(R₁ + R₂) || (R₃ + R₄ + R₅)

Atoms within a semiconductor crystal are held together by:

Covalent bonds

The valence band

Atomic glue

Subatomic particles

Covalent bonds

A logic circuit that provides a HIGH output if one input or the other input, but not both, is HIGH, is a(n):

Ex-OR gate

NAND gate

Ex-NOR gate

OR gate

Ex-OR gate

In the figure below, a voltmeter connected across R_L reads zero. Most probably:

the base collector junction of the transistor has gone open circuit

R_L has open-circuited

None of the choices

the V_cc supply battery is flat

the base collector junction of the transistor has gone open circuit

What is the difference between a 7400 and a 7411 IC?

7400 has four two-input NAND gates; 7411 has three three-input AND gates

7400 has two four-input AND gates; 7411 has three three-input NAND gates

7400 has two four-input NAND gates; 7411 has three three-input AND gates

7400 has four two-input AND gates; 7411 has three three-input NAND gates

7400 has four two-input NAND gates; 7411 has three three-input AND gates

Reluctance in magnetic circuit is analogous to ____ in an electric circuit.

voltage

power

resistance

current

resistance

Pentavalent impurities:

introduce holes when added to a semiconductor material

are introduced by adding aluminum atoms to a semiconductor material

increase a condition of a semiconductor material

have three valency electrons

increase a condition of a semiconductor material

Which of the following statements is false?

In a single-phase transformer, the hysteresis loss is proportional to frequency

In an ideal transformer, the volts per turn are constant for a given value of primary voltage

A transformer whose secondary current is greater than the primary current is a step-up transformer

In transformers, eddy current loss is reduced by laminating the core

A transformer whose secondary current is greater than the primary current is a step-up transformer

When the collector resistor in a CE amplifier is increased in value, the voltage gain:

Increases

Is not affected

Decreases

Become erratic

Increases

The slip speed of an induction motor:

is zero until the rotor moves and then rises slightly

is zero until the rotor moves and then rises to 100 per cent

is 100 per cent until the rotor moves and then falls to a low value

is 100 per cent until the rotor moves and then decreases slightly

is 100 per cent until the rotor moves and then falls to a low value

When you connect an ammeter in a series resistive circuit and turn on the source voltage, the ammeter reads zero. You should check for:

Both a broken wire and an open resistor

A broken wire

A shorted resistor

An open resistor

Both a broken wire and an open resistor

With surface-mount technology (SMT), the devices should:

mount directly

have parallel connecting pins

require holes and pads

utilize transistor outline connections

mount directly

When one of four series resistors is removed from a circuit and the circuit reconnected, the current

increases

decreases by one-fourth

quadruples

decreases by the amount of current through the removed resistor

increases

If you have an RC and an RL differentiator with equal time constants sitting side-by-side and you apply the same input pulse to both,

the RC has the widest output pulse

the RL has the most narrow spikes on the output

you cant tell the difference by observing the output waveforms

the output of one is an increasing exponential and the output of the other is a decreasing exponential

you cant tell the difference by observing the output waveforms

A TTL totem-pole circuit is designed so that the output transistors:

provide voltage regulation

provide phase splitting

are never on together

are always on together

are never on together

A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is increased, the voltage induced across the coil will _____.

remain the same

decrease

be excessive

increase

increase

Iron losses in a transformer are due to:

The resistance of the primary and secondary windings

Eddy currents only

Flux leakage

Both eddy current and hysteresis losses

Both eddy current and hysteresis losses

An advantage of an auto-transformer is that:

It reduces capacitance between turns

Copper loss is reduced

Iron losses are reduced

It gives a high step-up ratio

Copper loss is reduced

The resonant frequency of parallel circuit is the same as a series circuit using the same components when:

None of the choices

The Q is very high

There is no resistance

The Q is very low

The Q is very high

The output voltage of balanced Wheatstone bridge is:

Dependent on the value of the unknown resistor

Equal to zero

Dependent on all of the resistor values in the bridge

Equal to a source voltage

Equal to zero

A logic probe is placed on the output of a gate and the display indicator is dim. A pulser is used on each of the input terminals, but the output indication does not change. What is wrong?

The dim indication on the logic probe indicates that the supply voltage is probably low.

The gate is a tristate device.

The dim indication is the result of a bad ground connection on the logic probe.

The output of the gate appears to be open.

The output of the gate appears to be open.

A commutator is a device fitted to a generator. Its function is:

To generate a direct current

To convey the current to and from the windings

To convert the a.c. generated into a d.c. output

To prevent sparking when the load changes

To generate a direct current

The speed of a d.c. motor may be increased by:

Decreasing the field current

Increasing the field current

Increasing the armature current

Decreasing the applied voltage

Decreasing the field current

Why is an exclusive-NOR gate also called an equality gate?

The output is true if the inputs are opposite.

None of the choices

The output is true if the inputs are equal.

The output is false if the inputs are equal.

The output is true if the inputs are equal.

A sudden decrease in a total current into a parallel circuit may indicate:

An open resistor

Either an open resistor or a drop in source voltage

A short

A drop in source voltage

Either an open resistor or a drop in source voltage

The systematic reduction of logic circuits is accomplished by:

using a truth table

symbolic reduction

TTL logic

using Boolean algebra

using Boolean algebra

In a class A amplifier, the output signal is _____.

clipped

smaller in amplitude than the input

distorted

the same shape as the input

the same shape as the input

A network designed to pass signals with frequencies between two specified cut-off frequencies is called a ____ filter.

high-pass

low-pass

band-pass

band-stop

band-pass

What is the advantage of using CMOS logic over TTL?

It is larger.

It switches faster.

Cost

It uses less power.

It uses less power.

In the crankshaft position sensor in the figure below, the induced voltage across the coils is caused by:

a tab passing through the magnetic field

acceleration of the disk`s rotational speed

current in the coil

rotation of the disk

a tab passing through the magnetic field

In a series RC circuit, 10 V rms is measured across the resistor and 10 V rms is also measured across the capacitor. The voltages are measured at a certain frequency. To make the resistor voltage greater than the capacitor voltage, the frequency

must be decreased

must be increased

has no effect

is held constant

must be increased

In an RC differentiator, the output pulse closely resembles the input when

T is less than the pulse width

T is much larger than the pulse width

T is much less than the pulse width

T is equal to the pulse width

T is much larger than the pulse width

When RC is much larger (greater than 10RC) than the pulse width the output waveform resembles the square wave of the input signal.

Which of the following statements is false?

The circuit impedance is a maximum at resonance in a parallel circuit

The supply current is a minimum at resonance in a parallel circuit

Improving power factor reduces the current flowing through a system

The Q-factor at resonance in a parallel circuit is the voltage magnification

The Q-factor at resonance in a parallel circuit is the voltage magnification

Which of the following statements relating to operational amplifiers is true?

It has a low open-loop voltage gain at low frequency, a high input impedance and low output impedance

It has a high open-loop voltage gain at low frequency, a low input impedance and low output impedance

It has a high open-loop voltage gain at low frequency, a high input impedance and low output impedance

It has a high open-loop voltage gain at low frequency, a low input impedance and high output impedance

It has a high open-loop voltage gain at low frequency, a high input impedance and low output impedance

Which of the following series combination dissipates the most power when connected across a 100 V source?

Three 100 ohms resistors

Two 100 ohms resistors

Four 100 ohms resistors

One 100 ohms resistor

One 100 ohms resistor

The electron activation of a movable shaft is the basis for:

Magnetic switches

Solenoids

Relays

Circuit breaker

Solenoids

If you measure all the voltage drops and the source voltage in a series circuit and add them together, taking into consideration the polarities, you will get a result equal to:

The total of the voltage drops

The source voltage

The total of the source voltage and the voltage drops

Zero

Zero

The commutative law of addition and multiplication indicates that:

the way we OR or AND two variables is unimportant because the result is the same

the factoring of Boolean expressions requires the multiplication of product terms that contain like variables

we can group variables in an AND or in an OR any way we want

an expression can be expanded by multiplying term by term just the same as in ordinary algebra

the way we OR or AND two variables is unimportant because the result is the same

Which of the following statements is false? When two metal electrodes are used in a simple cell, the one that is higher in the electrochemical series:

Tends to dissolve in the electrolyte

Acts as an anode

Reacts most readily with oxygen

Is always the negative electrode

Acts as an anode