ECT Pre Board Exam 1

Two basic uses for transformers are:

signal matching and power supplies.

power supplies and bias control.

voltage regulation and rectification.

signal matching and voltage regulation.

signal matching and power supplies.

A rectangle with area 21 and one side of length 3 has one vertex at the point (0,0) on the rectangular coordinate plane. Which of the following points could lie on the interior of this rectangle?

(0, 4)

(5, 2)

(7, 1)

(4, 4)

(5, 2)

At a certain time of day, a 25-foot-tall radio antenna casts a 7 foot-long shadow. What is the length of the shadow of a 90-foot-tall radio antenna at the same time?

15-1/2

25-1/5

14

18

25-1/5

What components value is measured in millihenries?

Capacitor

Resistor

Diode

Inductor

Inductor

In a linear electronic voltage regulator:

The output is a ramp voltage.

The pass transistor switches from the off state to the on state.

The conduction of a control element is varied in direct proportion to the line voltage or load current.

The control device is switched on or off, with the duty cycle proportional to the line or load conditions.

The conduction of a control element is varied in direct proportion to the line voltage or load current.

What shall be used to measure the velocity of propagation?

Neither RF network analyzer or metallic time domain reflectometer

Either RF network analyzer or metallic time domain reflectometer

Metallic time domain reflectometer

RF network analyzer

Either RF network analyzer or metallic time domain reflectometer

In data communications, a ______ is a place of convergence where data arrives from one or more directions and then forwarded to one or more other directions.

box

jack

hub

switch

hub

In the circuit below, what is the voltage output at letter "X", when input voltage is 25V?

25 V

5 V

10 V

15 V

10 V

In telecommunications, a computer, phone and fax machine are defined as ________.

device

neither equipment nor device

equipment

either equipment or device

equipment

In a series resistive and reactive circuit what formula is used to find total impedance?

Z = sqrt(R² + X²)/2

Z = X²(R²/2)

Z = sqrt(R² + X²)

Z = R²(X²/2)

Z = sqrt(R² + X²)

Voltage or potential difference is the measure of potential energy between two points in a circuit and is commonly referred to as:

potential resistance.

voltage flow.

voltage drop.

difference in conduction.

voltage drop.

Zener diodes are designed to operate in the _____ bias region.

reactive

reverse

depletion

forward

reverse

How does the gain of a parabolic dish antenna change when the operating frequency is doubled?

Gain increases 3 dB.

Gain increases 6 dB.

Gain is multiplied by 0.707.

Gain does not change.

Gain increases 6 dB.

The formula to calculate dBm from mW is:

10 log10 (P/ 0.5mW)

20 log10 (P/1mW)

10 log10 (P²/1mW)

10 log10 (P/1mW)

10 log10 (P/1mW)

Current in a parallel circuit is:

equal to the sum of the branch resistances.

inversely proportional to the circuits resistance.

equal to the voltage source, minus the branch resistances.

equally divided among each branch.

inversely proportional to the circuits resistance.

Which of the following is the most common connector used in telecom?

4P4C

RJ-11or RJ-25

RJ-45

All choices are correct

All choices are correct

A MOSFET is comprised of what four elements?

Base, source, drain and dielectric

Dielectric, source, drain and base

Gate, source, drain and substrate

Gate, source, collector and substrate

Gate, source, drain and substrate

Bohr's Atomic Model consists of what three components?

Protons, neutrons and cations

Protons, neutrons and electrons

Neutrons, ion, neutrinos

Tachyons gravitons and electrons

Protons, neutrons and electrons

What are the three basic parts of a transformer?

Primary winding, secondary winding and tertiary winding

Primary winding, secondary winding and core

Primary winding, dielectric and core

Primary winding, power diode and secondary winding

Primary winding, secondary winding and core

A sound changes in volume by - 13 dB. If the original sound power is 1 W, what is the final sound power?

80 mW

50 mW

60 mW

70 mW

50 mW

Current amounts between ______ and _____ can be lethal.

33.3 mA, 75.6 mA

100 mA, 200 mA

10 mA, 33.3 mA

4 mA, 10 mA

100 mA, 200 mA

The ideal method of removing insulation from wire is:

The scissor action stripping tool.

The thermal stripper.

A mechanical wire stripper.

The pocket knife.

The thermal stripper.

When the frequency of an applied voltage is increased the capacitive reactance of a circuit will:

increase.

short all capacitors to ground.

stay unchanged.

decrease.

decrease.

What is the radix of the hexadecimal number system?

16

8

32

2

16

Which of the following equations represents this information: "Engr. Cuervo distributed 85 breakers among the z students in his science class? Each student received 5 breakers."

5z = 85

z = 5/85

5 = z/85

85z = 5

5z = 85

Which bipolar transistor configuration has a current gain of less than 1?

Common collector

Common emitter

Emitter follower

Common base

Common base

What IEEE standard is for Ethernet?

802.3af

802.3

802.11

802.2

802.3

The time required to charge a capacitor to 63 percent is known as:

Thevenin`s constant.

a linear superposition.

a time constant.

Tau.

a time constant.

Total resistance in a series circuit equals:

the average value of the voltage drops across each resistor within the circuit.

the sum of all the resistor values within the circuit.

The sum of the power dissipated by each resistor.

half the measured resistance multiplied by the applied voltage.

the sum of all the resistor values within the circuit.

the sum of all the resistor

For current to flow in an NPN silicon transistor's emitter-collector junction, the base must be:

At least 0.7 volts negative with respect to the emitter.

At a negative voltage with respect to the emitter.

At least 0.4 volts positive with respect to the emitter.

At least 0.7 volts positive with respect to the emitter.

At least 0.7 volts positive with respect to the emitter.

To properly bias the NPN transistor below, which voltages are correct?

E = +3; B = +1; C = -7

E = -1; B = +1; C = +10

E = 0; B = 0; C = +12

E = -1.7; B = -2.7; C = -5

E = -1; B = +1; C = +10

If you have a 12-strand conductor and each strand has a radius (one-half the diameter) of 2/10 inch, what is the circular mil area of the conductor?

1,920,000

1,822,400

1,057,680

1,248,000

1,920,000

What shall be used to measure frequency response and cable loss of coaxial cable?

Neither RF network analyzer or metallic time domain reflectometer

RF network analyzer

Either RF network analyzer or metallic time domain reflectometer

Metallic time domain reflectometer

RF network analyzer

When compared to a JFET, the base of a bipolar transistor is similar to what element of the JFET?

Source

Emitter

Gate

Drain

Gate

The expression "voltage regulation" as it applies to a shunt-wound DC generator operating at a constant frequency refers to:

Voltage output efficiency.

Rotor winding voltage ratio

Voltage in the secondary compared to the primary.

Voltage fluctuations from load to no-load.

Voltage fluctuations from load to no-load.

A sphere with a radius of 4 is inscribed in a cube whose edge length is 8. What is the distance from the center of the sphere to a corner of the cube?

8 sqrt 3

8

4 sqrt 3

8 sqrt 2

4 sqrt 3

What is the number one concern in regards to electrical safety?

Faulty equipment

ESD

Proper grounding

Shock

Shock

Silicon diodes have an approximate voltage drop of:

0.9V

1.414V

0.7V

0.3V

0.7V

Which of the following expressions is equivalent to (2x² - 4x - 16)/(x² - 3x - 4)?

(2x + 4)/(x + 1)

(2x - 4)/(x - 1)

x² + 4x/3 + 4

x² - x - 12

(2x + 4)/(x + 1)

Electrons are arranged in _____ around a nucleus.

orthogonal lattices

spheres

loops

shells

shells

Josh sells a total of 225 bagels and muffins in one day at his cafe. If the number of muffins he sells is 15 more than twice the number of bagels sold, how much bagels does he sell?

60

70

80

145

70

The National Building Code of the Philippines is Presidential Decree No. _______.

1096

1069

1609

1690

1096

In the circuit below, what is the calculated power for R₃?

41.3 W

47.1 W

45.8 W

43.2 W

43.2 W

An analog multimeter (AMM) checks for:

current, resistance and capacitance.

voltage, resistance and capacitance.

voltage, current and resistance.

voltage, resistance and inductance.

voltage, current and resistance.

All of the students in a history class are juniors or seniors. There are twice as many girls as boys in the class and there are 3 times as many senior girls as junior girls. If a student is selected at random, what is the probability that the student is a junior girl?

1/4

1/8

1/6

1/2

1/6

What is the product of all of the positive integers factors of 10?

50

10

100

200

100

A piggy bank is full of just nickels and dimes. If the bank contains 65 coins with a total value of 5 dollars, how many nickels and how many dimes are in the bank?

32 nickels and 33 dimes

30 nickels and 35 dimes

28 nickels and 37 dimes

25 nickels and 40 dimes

30 nickels and 35 dimes

Using a scientific calculator, a 3300 ohm resistor can be entered with scientific notation as:

3.3 x 10³

330 x 10²

33 x 10³

3.3 x 10²

3.3 x 10³

What is the digital gate equivalent for the circuit below?

NAND

NOR

OR

AND

NOR

At a car dealership, each of three cars must be parked in one of six adjacent parking spaces, provided that there is exactly one empty parking space between any two occupied spaces. How many ways can the three cars be arranged in the six spaces?

16

20

12

4

12