ECT Pre Board Exam 2

The following combination of 28 ohm resistors has a total resistance of 42 ohm:

three resistors in parallel

a combination of two resistors in parallel, then placed in series with another resistor

a combination of two resistors in parallel, then placed in series with another two in parallel

three resistors in series

a combination of two resistors in parallel, then placed in series with another resistor

_______ is a system consisting of an addressable fire alarm control panel and addressable devices that primarily give the exact location of a fire, among other features.

Conventional system

Addressable system

Fire detection system

Fire alarm system

Addressable system

What is symbolized in the figure?

Earth ground

Chassis ground

Back ground

Common ground

Chassis ground

An earth wire should be connected to the metal chassis of a mains-operated power supply to ensure that if a fault develops, the chassis:

provides a path to ground in case of lightning strikes

becomes a conductor to bleed away static charge

does not develop a high voltage with respect to the phase lead

does not develop a high voltage with respect to earth

does not develop a high voltage with respect to earth

_______ is a component of an electricity supply system, which divides an electrical power feed into subsidiary circuits, while providing a protective fuse or circuit breaker for each circuit, in a common enclosure.

Switchboard

Alternating current panel distribution board

Circuit breaker

Circuit panel board

Alternating current panel distribution board

In a certain game, players receive a different number of points for catching a ball in different zones of a field colored either yellow or green. One player caught 2 balls in the yellow zone and 3 balls in the green zone for a score of 31. Another player caught 3 balls in the yellow zone and 1 ball in the green zone for a score of 22. How many points are earned from a ball caught in the yellow zone?

5

8

6

7

5

The correct color coding for the neutral wire in a flexible mains lead is:

blue

yellow and green

brown they have a high electrical resistivity

white

blue

The following unit in a DC power supply performs a smoothing operation:

a crowbar

a full-wave diode bridge

a fuse

an electrolytic capacitor

an electrolytic capacitor

A flux density of 1.2 T is produced in a piece of cast steel by a magnetizing force of 1250 A/m. Find the relative permeability of the steel under these conditions.

750

564

659

764

764

If the sum of a and b is c, what is the average (arithmetic mean) of a and b in terms of a, b and c?

(a + b)/c

2c

c - (a + b)

c/2

c/2

For a moving-coil meter movement, I_M is

the value of current flowing in the moving-coil for any amount for pointer deflection.

None of the choices

the amount of current needed in the moving-coil to produce full scale deflection of the meter`s pointer.

the amount of current required in the moving-coil to produce half-scale deflection of the meter`s pointer.

the amount of current needed in the moving-coil to produce full scale deflection of the meter`s pointer.

For a particular silicon diode, V_F is 0.9 V and the bulk resistance is 0.5 Ω. What is the corresponding value if I_F?

500 mA

400 mA

300 mA

200 mA

400 mA

Which variety of copper has the best conductivity?

Copper containing traces of silicon

Hard drawn copper

Induction hardened copper

Pure annealed copper

Pure annealed copper

One way to operate a 3 volt bulb from a 9 volt supply is to connect it in:

parallel with the supply

series with the supply

parallel with a resistor

series with a resistor

series with a resistor

Antennas used in a distributed antenna system come in two-class types, namely _______.

omnidirectional and directional/panel antenna

micro and macro antenna

internal and external antenna

pico and micro antenna

omnidirectional and directional/panel antenna

Find the resistance of 800 m of copper cable of cross-sectional area 20 mm². Take the resistivity of copper as 0.02 μΩm.

8.0 Ω

0.008 Ω

0.8 Ω

0.08 Ω

0.8 Ω

Emelie is twice as old as her sister, Lisa. In 5 years, Lisa will be the same age as her sister was 10 years ago. What are their current ages?

Lisa is 12 years old and Emelie is 24 years old

Lisa is 23 years old and Emelie is 46 years old

Lisa is 20 years old and Emelie is 40 years old

Lisa is 15 years old and Emelie is 30 years old

Lisa is 15 years old and Emelie is 30 years old

Triangle ABC is equilateral and has an area of 1-3/5. Point D is the midpoint of side AB, point E is the midpoint of side BC and point F is the midpoint of side AC. What is the area of the parallelogram DECF?

4/5

13/15

2/5

2/3

4/5

When the base and height of an isosceles right triangle are each decreased by 4, the area decreases by 72. What is the height of the original triangle?

16

4

20

8

20

One precaution to observe when checking resistors with an ohmmeter is to:

check low resistance on the highest ohms range.

make sure your fingers are touching each test lead.

disconnect all parallel paths.

check high resistance on the lowest ohms range

disconnect all parallel paths.

A residual current device is recommended for protection in a mains power circuit because it:

removes power to the circuit when the phase and neutral currents are not equal

removes power to the circuit when the current in the phase wire equals the current in the earth wire

limits the power provided to the circuit

reduces electrical interference from the circuit

removes power to the circuit when the phase and neutral currents are not equal

When using a DMM to measure the value of a resistor:

make sure there is no voltage present across the resistor.

Both make sure there is no voltage present across the resistor and make sure there is no other component connected across the leads of the resistor.

make sure that the resistor is in a circuit where voltage is present.

make sure there is no other component connected across the leads of the resistor

Both make sure there is no voltage present across the resistor and make sure there is no other component connected across the leads of the resistor.

What device is used with a subscriber's TV to allow reception of television program?

Optical Network Terminal (ONT)

Premises Connection Device (PCD)

Set Top Terminal (STT)

Optical Line Terminal (OLT)

Set Top Terminal (STT)

For your safety, before checking a fault in a mains operated power supply unit, first:

short the leads of the filter capacitor

turn off the power and remove the power plug

check the action of the capacitor bleeder resistance

remove and check the fuse in the power supply

turn off the power and remove the power plug

A nickel-cadmium cell has an operating voltage of about:

1.25 volts.

1.5 volts.

2.1 volts.

1.4 volts.

1.25 volts.

A check of all power supply voltages should be made during the ________ method of troubleshooting.

final test

diagnosis

repair

half-split

half-split

What is the name of an electrical wiring diagram that uses standard component symbols?

Bill of materials

Connector pinout

Schematic

Flow chart

Schematic

What is the resonant frequency in an electrical circuit?

The lowest frequency that will pass current.

The frequency which capacitive reactance equals inductive reactance.

The highest frequency that will pass current.

The frequency at which power factor is at a minimum

The frequency which capacitive reactance equals inductive reactance.

Filter capacitors in power supplies are sometimes connected in series to:

resonate the filter circuit

increase the total capacity

withstand a greater voltage than a single capacitor can withstand

reduce the ripple voltage further

withstand a greater voltage than a single capacitor can withstand

An isolating transformer is used to:

ensure that no voltage is developed between the output leads

step down the mains voltage to a safe value

ensure that no voltage is developed between either output lead and ground

ensure that faulty equipment connected to it will blow a fuse in the distribution board

ensure that no voltage is developed between either output lead and ground

The correct color coding for the phase wire in a flexible mains lead is:

white

yellow and green

blue

brown

brown

To direct microwaves in narrow beams for point-to-point communication links or radiolocation (radar), a ______ is usually used.

Marconi antenna

parabolic antenna

Yagi-Uda antenna

omni directional antenna

parabolic antenna

______ is an appliance designed to protect electrical devices from voltage spikes.

Transient voltage surge suppressor (TVSS)

Alternating current panel distribution board (ACPDB)

Automatic voltage regulator (AVR)

Busbar

Transient voltage surge suppressor (TVSS)

The main reason why Ni-Zn ferrites are used for audio and T.V. transformers is that:

they are totally free from pores and voids

they are easy to fabricate by rolling

they have large saturation magnetization

they have a high electrical resistivity

they have large saturation magnetization

What does the horizontal axis of a spectrum analyzer display?

Frequency.

Amplitude.

Voltage.

Resonance.

Frequency.

When a lead-acid storage battery is being charged, a harmful effect to humans is:

Emission of oxygen.

Emission of hydrogen gas.

Internal plate sulfation may occur under constant charging.

Emission of chlorine gas.

Emission of hydrogen gas.

In a list of five integers, if the mode of the list is two less than the median, which of the following could be true?

The list contains three equal numbers.

The average (arithmetic mean) is less than the median.

The mode is greater than the average (arithmetic mean).

The average (arithmetic mean) is equal to the mode.

The average (arithmetic mean) is less than the median.

You can safely remove an unconscious person from contact with a high voltage source by:

wrapping the person in a blanket and pulling to a safe area

pulling an arm or a leg

calling an electrician

turning off the high voltage and then removing the person

turning off the high voltage and then removing the person

At the ends of a half-wave antenna, what values of current and voltage exist compared to the remainder of the antenna?

Maximum voltage and minimum current.

Minimum voltage and maximum current.

Equal voltage and current.

Minimum voltage and minimum current.

Maximum voltage and minimum current.

What is the function of component 2 in the figure?

Supply electrical energy

Give off light when current flows through it

Convert electrical energy into radio waves

Control the flow of current

Control the flow of current

An ammeter should not be connected directly across the terminals of a 12 volt car battery because:

the resulting high current will probably destroy the ammeter

no current will flow because no other components are in the circuit

the battery voltage will be too low for a measurable current to flow

the battery voltage will be too high for a measurable current to flow

the resulting high current will probably destroy the ammeter

Section 17 of R. A. No. 9292 states that the Board and the Commission shall correct and rate the licensure examination papers and shall release the examination results within ____ days after the said examination.

5

15

3

7

15

A transformer has a 240 volts primary that draws a current of 250 mA from the mains supply. Assuming no losses, what current would be available from a 12-volt secondary?

50 A

15 A

5 A

25 A

5 A

What is a device that transforms incoming optical signals into electrical signals and vice versa at a customer's premises?

Set Top Terminal (STT)

Optical Network Terminal (ONT)

Premises Connection Device (PCD)

Optical Line Terminal (OLT)

Optical Network Terminal (ONT)

What is the voltage across each of two components in series with a voltage source?

It is determined by the type and value of the components

Twice the source voltage

Half the source voltage

The same voltage as the source

It is determined by the type and value of the components

An impure signal is found to have 2 kHz and 4 kHz components. This 4 kHz signal is:

a sub-harmonic of 2 kHz

a harmonic of the 2 kHz signal

a fundamental of the 2 kHz signal

the DC component of the main signal

a harmonic of the 2 kHz signal

A 10-ohm and a 20-ohm resistance are connected in parallel. Another resistance of 5-ohm is connected in series with the two. If the supply voltage is 48 volts, what is the current through the 10-ohm resistance?

4.02 A

3.21 A

2.74 A

5.72 A

2.74 A

One essential step to ensure the success of a microgravity bean seed germination project is that 10 gallons of a 70% concentrated nutrient solution be administered to the bean seeds. If the payload specialist has some 90% nitrogen and some 30% nitrogen, how many gallons of each should she mix in order to obtain the desired solution?

6.67 gallons of 30% nitrogen solution with 3.33 gallons of 90% nitrogen solution

2.5 gallons of 30% nitrogen solution with 7.5 gallons of 90% nitrogen solution

3.33 gallons of 30% nitrogen solution with 6.67 gallons of 90% nitrogen solution

7.5 gallons of 30% nitrogen solution with 2.5 gallons of 90% nitrogen solution

3.33 gallons of 30% nitrogen solution with 6.67 gallons of 90% nitrogen solution

The use of a logic probe may be improved through the use of a(n) ________.

frequency counter

logic clip

oscilloscope

current tracer

logic clip

________ is an FDAS component containing one or more indicator lamps/LEDs or alphanumeric displays in which each indication provides status information about an addressable or conventional devices, a group of devices, a zone , a circuit or an LCD and graphic condition.

Annunciator

Alarm device

Detector

None of the choices

Annunciator