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100問 • 2年前

問題一覧

Lines of the magnetic field produced by a long straight wire carrying a current are

circles that are concentric with the wire

Which is/are permitted for branch disconnecting means of a second building? I. Inside the building near service entrance II. Outside the building but accessible

I and II

The primary function of a fuse is to _____.

Protect the line

An SCR combines the features of

a rectifier and transistor

The permissible variation in supply frequency is

+- 5%

In circuit breaker the time duration from the instant of fault to the instant of energizing of the trip coil is known as

protection time

The characteristics impedance of a loss-less overhead line has a value of

400 to 600 ohms

A conductor has seven identical strands of r = 1 cm each. The GMR of the conductor is

2.177 cm

Dwelling receptacles located ____ m above floors are NOT counted in the required number of receptacles along the wall.

1.8

The fault current that exists immediately after the fault is known as:

sub-transient current

The presence of earth alters the

Current reactors are used to _____

Bring down the fault level within the capacity

This is an electrically operated switch which is rated in amperes and is also used in overload protection of motors.

magnetic contactor

Factors involved in fixing tariff are

all of these

What is the burning hours that should be used in the design consideration of incandescent bulb?

1500

Which of this is not a factor in the selection of fuse rating for protection of a branch circuit.

System impedance

Which of the following conductors has the highest resistance?

nichrome

If the reverse bias voltage of a PN junction is increases within the limits, the reverse saturation current will ________

Remain unaffected

According to Flemming's rights hand rule for finding the direction of the induced emf, the forefinger points the direction of which of the following?

Lines of force

When a conductor is stationary and the magnetic field is moving or changing, what type of emf is induced?

Statically induced emf

At super conductivity condition, what happens to the resistivity of the material?

It reduces to zero

In a single-phase induction motor, the centrifugal switch is connected where?

In series with the starting winding

James Chadwick got the Nobel Prize for the discovery of which of the following?

Neutrons

What is the name of the area within a semiconductor diode where no mobile current carriers exist when it is formed?

Depletion region

The h-parameters of a transistor depend on its

all of the above

The magnetic coupling between the primary and secondary windings of a transformer can be increased by which of the following methods?

By using a magnetic core material of low reactance

Which one is true about an alkaline cell in comparison to a carbon-zinc cell?

It generally works better in transistor radios

For power factor correction of a welding transformer, a capacitor is usually connected where?

In the primary side

A load curve indicates

average kWh (kW) energy consumption during the period

The essential condition for parallel operation of two 1-phase transformers is that they should have the same

polarity

In a dc 3-wire distributor using balancers and having unequal loads on the two sides

balancer connected to a lightly-loaded side runs as a motor

The frequency corresponding to half- power point on the response curve of a filter is known as ____

cutoff

_____ bridge is used for measuring an unknown inductance in terms of a known capacitance and resistance

Anderson

Which one is a cause for the over voltage surges in power system?

All of these

Contacts of high voltage switches used in power systems are immersed in oil. What is the purpose of the oil?

To extinguish the arc

What term is used to describe the maximum reverse voltage that can be applied to an ordinary semiconductor diode without damaging itself?

Peak inverse voltage

The capacitance of a capacitor is _____ relative permitivity?

directly proportional to

A low utilization factor for a plant indicates that

plant used for standby purpose only

In a capacitor-start motor, what is the phase displacement between the starting and running windings?

A synchronous motor is cheaper than a 3-phase induction motor for which of the following load conditions?

Low speed, high output

Which one is the formula to solve the dynamic impedance of a parallel resonant circuit?

L/CR

The PIV of a half-wave rectifier circuit with a shunt capacitor filter is

In a dc machine, the biggest eddy current loss occurs when?

Armature cores

Which of the following would cause sparking at the brushes in a dc generator?

All of these

A circuit having identical properties in either direction is called _____

Bilateral Circuit

Which of the following motors has series characteristics?

Repulsion motors

Heaviside-Campbell Equal Ratio bridge is used for measuring

self-inductance in terms of mutual inductance

If the average value of a periodic function over one period is zero and it consists of only odd harmonics then it must be possessing ___symmetry.

half-wave

When an alternator connected to a bus bar is shut down, what happens to the bus bar voltage?

The voltage will remain the same

What is the device function number for overcurrent relay?

When a dc motor has no-load. what will happen to the back emf?

becomes maximum

A 4-way switch controls a lamp from different locations.

A device that establishes an electrical connection to the earth.

Grounding electrode

Once residual magnetism of a shunt generator is lost it may be restored by connecting its shunt field

to an external battery

Which of the following is not included in the evaluation of the Technical Performance of a Distribution System according to Philippine Distribution Code (PDC)?

collecting efficiency

It is defined as the total number of sustained Customer power Interruptions within a given period divided by the total number of Customers served within the same period.

System average interruption frequency index

Cellular phones operate in the frequency range of

UHF

If an electrical network having one or more than one voltage source is transformed into equivalent electrical network with a single current source (which is the short circuit current of previous circuit) with parallel internal resistance of the network with all current source replaced by their internal resistance; the above illustration is called

Nortons theorem

In a diode modulator, what supplies the negative halfwave?

Tuned Circuit

Transformer breaths in when

load on it decreases

Induced charge on insulators

Resides on surface

With reference to armature windings, wave windings are often called ______ windings.

Series

The voltage of a bus can be controlled by controlling the

reactive power of the bus.

Gauss-Siedel technique is commonly used in power systems for which of the following?

Load flow Analysis

For a load bus of a power system, the specified quantities are:

the real and reactive components of power

In a power system, each bus or node is associated with how many quantities?

Which of the following quantities are known on the generator bus?

V and P

What is the primary advantage of FM over AM?

Noise immunity

Which of the following shall be included in the calculation of the reliability standard indices of the distributor asset by the Philippine Distribution Code?

Outages that occur on the primary lines of the distribution system.

A magnetic field exerts a force on a charged particle:

if the particle is moving across the field lines

The direction of the magnetic field in a certain region of space is determined by firing a test charge into the region with its velocity in various directions in different trials. The field direction

one of the directions of the velocity when the magnetic force is zero

An electron is moving north in a region where the magnetic field is south. The magnetic force exerted on the electron is:

zero

A hydrogen atom that has lost its electron is moving east in a region where the magnetic field is directed from south to north. It will be deflected:

An electron travels due north through a vacuum in a region of uniform magnetic field B that is also directed due north. It will:

be unaffected by the field

At one instant an electron is moving in the positive a direction along the x axis in a region where there is a uniform magnetic field in the positive : direction. When viewed from a point on the positive z axis, it subsequent motion is:

counterclockwise around a circle in the zy plane

An electron and a proton are both initially moving with the same speed and in the same direction at 90° to the same uniform magnetic field. They experience magnetic forces, which

equal in magnitude but opposite in direction

For a loop of current-carrying wire in a uniform magnetic field the if the magnetic dipole moment of the loop is:

in the same direction as the field

The magnetic dipole moment of a current carrying loop of wire is in the positive z direction. If a uniform magnetic field is in the positive x direction the magnetic torque on the loop is:

in the positive y direction

A constant current is sent through a helical coil. The coil:

tends to get shorter

Helmholtz coils are commonly used in the laboratory because the magnetic field between them:

is nearly uniform

If the radius of a pair of Helmholtz coils is R then the distance between the coils is:

If R is the distance from a magnetic dipole, then the magnetic field it produces is proportional to:

1/R^3

A long straight cylindrical shell carries current i parallel to its axis and uniformly distributed over its cross section. The magnitude of the magnetic field is greatest:

at the outer surface of the shell

The magnetic field B inside a long ideal solenoid is independent of:

the cross-sectional area of the solenoid

Solenoid 2 has twice the radius and six times the number of turns per unit length as solenoid 1. The ratio of the magnetic field in the interior of 2 to that in the interior of 1 is:

A toroid with a square cross section carries current i. The magnetic field has its largest magnitude:

just inside the toroid at its inner surface

A toroid with a square cross section carries current i. The magnetic field has its largest magnitude:

just inside the toroid at its inner surface

A toroid has a square cross section with the length of an edge equal to the radius of the inner surface. The ratio of the magnitude of the magnetic field at the inner surface to the magnitude of the field at the outer surface is:

1 weber is the same as:

1 V*s

The units of motional emf are:

tesla-meter^2 /second

Faraday's law states that an induced emf is proportional to:

the rate of change of the magnetic flux

The emf that appears in Faraday's law is:

around the boundary of the surface used to compute the magnetic flux

An electric field is associated with every:

time-dependent magnetic field

The unit "henry" is equivalent to:

volt-second/ampere

If both the resistance and the inductance in an LR series circuit are doubled the new inductive time constant will be

unchanged

The stored energy in an inductor:

none of the above

An IC series circuit with an inductance L and a capacitance C has an oscillation frequency f. Two inductors, each with inductance L, and two capacitors, each with capacitance C, are all wired in series and the circuit is completed. The oscillation frequency is:

The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might be due to:

a large resistance

The impedance of an RL series circuit is definitely increased if:

R increases

100

When the amplitude of the oscillator in a series RLC circuit is doubled:

the current amplitude is doubled

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問題一覧

Lines of the magnetic field produced by a long straight wire carrying a current are

circles that are concentric with the wire

Which is/are permitted for branch disconnecting means of a second building? I. Inside the building near service entrance II. Outside the building but accessible

I and II

The primary function of a fuse is to _____.

Protect the line

An SCR combines the features of

a rectifier and transistor

The permissible variation in supply frequency is

+- 5%

In circuit breaker the time duration from the instant of fault to the instant of energizing of the trip coil is known as

protection time

The characteristics impedance of a loss-less overhead line has a value of

400 to 600 ohms

A conductor has seven identical strands of r = 1 cm each. The GMR of the conductor is

2.177 cm

Dwelling receptacles located ____ m above floors are NOT counted in the required number of receptacles along the wall.

1.8

The fault current that exists immediately after the fault is known as:

sub-transient current

The presence of earth alters the

Current reactors are used to _____

Bring down the fault level within the capacity

This is an electrically operated switch which is rated in amperes and is also used in overload protection of motors.

magnetic contactor

Factors involved in fixing tariff are

all of these

What is the burning hours that should be used in the design consideration of incandescent bulb?

1500

Which of this is not a factor in the selection of fuse rating for protection of a branch circuit.

System impedance

Which of the following conductors has the highest resistance?

nichrome

If the reverse bias voltage of a PN junction is increases within the limits, the reverse saturation current will ________

Remain unaffected

According to Flemming's rights hand rule for finding the direction of the induced emf, the forefinger points the direction of which of the following?

Lines of force

When a conductor is stationary and the magnetic field is moving or changing, what type of emf is induced?

Statically induced emf

At super conductivity condition, what happens to the resistivity of the material?

It reduces to zero

In a single-phase induction motor, the centrifugal switch is connected where?

In series with the starting winding

James Chadwick got the Nobel Prize for the discovery of which of the following?

Neutrons

What is the name of the area within a semiconductor diode where no mobile current carriers exist when it is formed?

Depletion region

The h-parameters of a transistor depend on its

all of the above

The magnetic coupling between the primary and secondary windings of a transformer can be increased by which of the following methods?

By using a magnetic core material of low reactance

Which one is true about an alkaline cell in comparison to a carbon-zinc cell?

It generally works better in transistor radios

For power factor correction of a welding transformer, a capacitor is usually connected where?

In the primary side

A load curve indicates

average kWh (kW) energy consumption during the period

The essential condition for parallel operation of two 1-phase transformers is that they should have the same

polarity

In a dc 3-wire distributor using balancers and having unequal loads on the two sides

balancer connected to a lightly-loaded side runs as a motor

The frequency corresponding to half- power point on the response curve of a filter is known as ____

cutoff

_____ bridge is used for measuring an unknown inductance in terms of a known capacitance and resistance

Anderson

Which one is a cause for the over voltage surges in power system?

All of these

Contacts of high voltage switches used in power systems are immersed in oil. What is the purpose of the oil?

To extinguish the arc

What term is used to describe the maximum reverse voltage that can be applied to an ordinary semiconductor diode without damaging itself?

Peak inverse voltage

The capacitance of a capacitor is _____ relative permitivity?

directly proportional to

A low utilization factor for a plant indicates that

plant used for standby purpose only

In a capacitor-start motor, what is the phase displacement between the starting and running windings?

A synchronous motor is cheaper than a 3-phase induction motor for which of the following load conditions?

Low speed, high output

Which one is the formula to solve the dynamic impedance of a parallel resonant circuit?

L/CR

The PIV of a half-wave rectifier circuit with a shunt capacitor filter is

In a dc machine, the biggest eddy current loss occurs when?

Armature cores

Which of the following would cause sparking at the brushes in a dc generator?

All of these

A circuit having identical properties in either direction is called _____

Bilateral Circuit

Which of the following motors has series characteristics?

Repulsion motors

Heaviside-Campbell Equal Ratio bridge is used for measuring

self-inductance in terms of mutual inductance

If the average value of a periodic function over one period is zero and it consists of only odd harmonics then it must be possessing ___symmetry.

half-wave

When an alternator connected to a bus bar is shut down, what happens to the bus bar voltage?

The voltage will remain the same

What is the device function number for overcurrent relay?

When a dc motor has no-load. what will happen to the back emf?

becomes maximum

A 4-way switch controls a lamp from different locations.

A device that establishes an electrical connection to the earth.

Grounding electrode

Once residual magnetism of a shunt generator is lost it may be restored by connecting its shunt field

to an external battery

Which of the following is not included in the evaluation of the Technical Performance of a Distribution System according to Philippine Distribution Code (PDC)?

collecting efficiency

It is defined as the total number of sustained Customer power Interruptions within a given period divided by the total number of Customers served within the same period.

System average interruption frequency index

Cellular phones operate in the frequency range of

UHF

Nortons theorem

In a diode modulator, what supplies the negative halfwave?

Tuned Circuit

Transformer breaths in when

load on it decreases

Induced charge on insulators

Resides on surface

With reference to armature windings, wave windings are often called ______ windings.

Series

The voltage of a bus can be controlled by controlling the

reactive power of the bus.

Gauss-Siedel technique is commonly used in power systems for which of the following?

Load flow Analysis

For a load bus of a power system, the specified quantities are:

the real and reactive components of power

In a power system, each bus or node is associated with how many quantities?

Which of the following quantities are known on the generator bus?

V and P

What is the primary advantage of FM over AM?

Noise immunity

Which of the following shall be included in the calculation of the reliability standard indices of the distributor asset by the Philippine Distribution Code?

Outages that occur on the primary lines of the distribution system.

A magnetic field exerts a force on a charged particle:

if the particle is moving across the field lines

The direction of the magnetic field in a certain region of space is determined by firing a test charge into the region with its velocity in various directions in different trials. The field direction

one of the directions of the velocity when the magnetic force is zero

An electron is moving north in a region where the magnetic field is south. The magnetic force exerted on the electron is:

zero

A hydrogen atom that has lost its electron is moving east in a region where the magnetic field is directed from south to north. It will be deflected:

An electron travels due north through a vacuum in a region of uniform magnetic field B that is also directed due north. It will:

be unaffected by the field

counterclockwise around a circle in the zy plane

An electron and a proton are both initially moving with the same speed and in the same direction at 90° to the same uniform magnetic field. They experience magnetic forces, which

equal in magnitude but opposite in direction

For a loop of current-carrying wire in a uniform magnetic field the if the magnetic dipole moment of the loop is:

in the same direction as the field

The magnetic dipole moment of a current carrying loop of wire is in the positive z direction. If a uniform magnetic field is in the positive x direction the magnetic torque on the loop is:

in the positive y direction

A constant current is sent through a helical coil. The coil:

tends to get shorter

Helmholtz coils are commonly used in the laboratory because the magnetic field between them:

is nearly uniform

If the radius of a pair of Helmholtz coils is R then the distance between the coils is:

If R is the distance from a magnetic dipole, then the magnetic field it produces is proportional to:

1/R^3

A long straight cylindrical shell carries current i parallel to its axis and uniformly distributed over its cross section. The magnitude of the magnetic field is greatest:

at the outer surface of the shell

The magnetic field B inside a long ideal solenoid is independent of:

the cross-sectional area of the solenoid

Solenoid 2 has twice the radius and six times the number of turns per unit length as solenoid 1. The ratio of the magnetic field in the interior of 2 to that in the interior of 1 is:

A toroid with a square cross section carries current i. The magnetic field has its largest magnitude:

just inside the toroid at its inner surface

A toroid with a square cross section carries current i. The magnetic field has its largest magnitude:

just inside the toroid at its inner surface

1 weber is the same as:

1 V*s

The units of motional emf are:

tesla-meter^2 /second

Faraday's law states that an induced emf is proportional to:

the rate of change of the magnetic flux

The emf that appears in Faraday's law is:

around the boundary of the surface used to compute the magnetic flux

An electric field is associated with every:

time-dependent magnetic field

The unit "henry" is equivalent to:

volt-second/ampere

If both the resistance and the inductance in an LR series circuit are doubled the new inductive time constant will be

unchanged

The stored energy in an inductor:

none of the above

The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might be due to:

a large resistance

The impedance of an RL series circuit is definitely increased if:

R increases

100

When the amplitude of the oscillator in a series RLC circuit is doubled:

the current amplitude is doubled