浙江大学国际联合学院（海宁国际校区）

Electrical safety Back

Single-choice question

Question 1

An important precaution against electric shock is to effectively ground the metal case of the electrical equipment. Please select a reliable grounding point from the following options:

A:The two wires of a single-phase power supply are respectively called the fire wire and ground wire.

B:The neutral point voltage in the three-phase supply shall be zero. This neutral point may be selected for grounding

C:Specially buried in the underground, ensure that the grounding resistance is small by using a special ground wire

D:The indoor water pipes (heating pipes) are connected with metal pipes, buried in the ground, and can be used for grounding

Correct answer：

C

Question 2

When using electrical equipment, what can cause a short circuit if maintenance is inadequate?

A:Conductive dust or fiber

B:Strong light radiation

C:High temperature environment

D:The moisture

Correct answer：

A

Question 3

What indication should be used to confirm that the equipment or line is without power?

A:Voltmeter

B:Normal electroscope

C:Disconnection signal

D:Ammeter

Correct answer：

B

Question 4

The power cord of the mobile power tool and its switch plate (box) must be:

A:Double-layer plastic copper core insulated cord

B:Double copper core plastic cord

C:Copper core rubber insulated sheath or copper core PVC insulated sheath cord

D:Single copper core plastic cord

Correct answer：

C

Question 5

Before using a hand-held electric tool that has not been used for a long time, we must measure the insulation resistance. It is required that the insulation resistance between the shell and the live part of the hand-held electric tool is not lower than ______MΩ?

A:2

B:0.5

C:1

D:10

Correct answer：

B

Question 6

For high voltage capacitors, what is the best way to dispose of them after the experiment or when they are idle?

A:Electrode grounding

B:Short connection of two electrodes (series connection of suitable resistance for discharge)

C:Double electrode grounding

D:Do not process

Correct answer：

B

Question 7

Among the following laboratory electricity consumption matters that need attention, which one is not true?

Correct answer：

C

Question 8

During power failure maintenance, which of the following signs should be hung on the operating handle of the switch or knife switch that can send power to the working place once the switch is closed?

Correct answer：

C

Question 9

Which of the following is not true when using a hand-held power tool?

A:Use a static blanket

B:Wear protective gloves

C:Use a leakage protector

D:Wear insulated shoes

Correct answer：

A

Question 10

Any electrical equipment shall be regarded as_______before it is verified to be without power.

A:There is no electricity

B:Maybe there is electricity

C:There is electricity

D:Maybe there is no electricity

Correct answer：

C

Question 11

In the circuit experiment, which of the following operations is False?

A:The voltage source cannot be short-circuited

B:The current source cannot be short-circuited

C:The current source can be short-circuited

D:All the above operations are true

Correct answer：

B

Question 12

When using electric irons:

A:Do not throw solder around

B:Put back to the soldering iron rack in time and cut off the power after use

C:Do not place flammable materials around

D:All of the above

Correct answer：

D

Question 13

After a multimeter is used, the switch knob should be placed in:

A:Resistance level

B:DC voltage level

C:Highest AC voltage level

D:Current level

Correct answer：

C

Question 14

Which of the following statements is True when a power cord is needed for the experiment?

A:It shall not be arbitrarily placed on the channel to avoid short-circuit or influence the traffic due to insulation damage

B:Continuous serial connection can be made in case of insufficient sockets

C:Continuous tap connection can be made in case of insufficient sockets

D:Load capacity is not considered

Correct answer：

A

Question 15

There is strong electricity and weak electricity. Which of the following statement is true?

A:Strong current and weak current switches and other components can be used generally

B:Weak current switch and other components should not be used in a strong current circuit

C:Switches do not have a strong or weak classification.

D:Weak current components such as weak current switches can be used in strong current circuit

Correct answer：

B

Question 16

Which of the following statements is true for low-voltage circuit experiment that requires hot-line operation?

A:Two-handed operation is safer than one-handed operation

B:One-handed operation is safer than two-handed operation

C:One-handed operation is as safe as two-handed operation

D:Operation is related to air humidity

Correct answer：

B

Question 17

How many experimenters must there be in high-voltage experiment?

A:1

B:2

C:3

D:4

Correct answer：

B

Question 18

Lightning releases huge amounts of energy due to the instantaneous strong current, which can not only hurt people, but also damage equipment and even cause fire. Please select one of the following options for the most important indoor lightning protection measures.

A:Lightning protection shall be installed on the top of high buildings and on the open air power distribution facilities.

B:Do not use the computer to surf the Internet during thunderstorms, and turn off the machine as much as possible, by unplugging the power source and network cable.

C:Do not use your cell phone during a thunderstorm

D:Do not use an electric soldering iron.

Correct answer：

A

Question 19

If the workplace is wet, to avoid electric shock, people using hand-held power tools should:

A:Stand on an iron plate.

B:Stand on the insulation board.

C:Wear anti-static shoes.

D:Wear a hard hat

Correct answer：

B

Question 20

When performing the foot cutting procedure after the welding of the electronic circuit board:

A:Wear protective glasses.

B:Wear ear protectors.

C:Put on your helmet.

D:Put on gloves

Correct answer：

A

Question 21

What measures should be taken to protect the enclosure of electrical equipment?

A:No

B:Protective grounding

C:Anti-rust paint

D:Insulation

Correct answer：

B

Question 22

In order to prevent electrostatic spark from causing accidents, it is necessary for the metal equipment and non-conductive materials for processing, storing, and transporting all kinds of easy gas, liquid, and powder to:

A:There is enough resistance.

B:Resistance is small enough

C:Reliably grounded

D:Reliably insulated

Correct answer：

C

Question 23

Friction is a major cause of static electricity, especially in a dry environment. The movement of the human body and objects will produce a strong static electricity. Static electricity in a sudden release that will cause damage to the human body and equipment. Which of the following is the main method to prevent static electricity accidents?

A:When the human body comes into contact with devices sensitive to static electricity, the electric charge accumulated in the body should be released in advance, such as by wearing a static electricity protection bracelet and using a static electricity protection blanket.

B:All electrical equipment is well grounded

C:Ensure good insulation of the circuit

D:Comb your hair in an area prone to static electricity.

Correct answer：

A

Question 24

Although the electric charge of static electricity is not large, the electrostatic spark generated during discharge may cause explosion or fire. It is common that the instantaneous electric current during discharge causes damage to precision experimental instruments. Which of the following preventive measures is not true?

A:Appropriately raise the humidity in the workplace.

B:During special hazard test, operators should first contact the metal grounding rod set in the safety zone to eliminate human potential.

C:Comb your hair in an area prone to static electricity.

D:Use anti-static blanket for computer maintenance.

Correct answer：

C

Question 25

Which of the following are the basic measures to prevent electrical fire?

A:It is forbidden for non-electricians to connect electrical lines, and it is forbidden to randomly pull temporary power lines.

B:Two or more people should be present when conducting an electrical experiment

C:Remove inflammable and explosive materials from the work site.

D:All of the above

Correct answer：

D

Question 26

In order to reduce the damage of an electric shock accident to human body, current leakage protection switch is often used, and its protection index is set to ≤30mAS. Select the true meaning from the following options.

A:The product of the current (in milliamps) and time (in seconds) flowing through the human body is less than 30. For example, if the current is 30mA, the duration must be less than 1 second.

B:The current flowing through the human body must be less than 30 mA.

C:The duration of current flowing through the body must be less than 1 second

D:The current flowing through the human body must be less than 30 μA.

Correct answer：

A

Question 27

Safety voltage refers to the voltage value that does not produce fatal danger to human body. Which of the following is the safety voltage that is used in industry?

A:25V

B:36V

C:50V

D:110V

Correct answer：

B

Question 28

Which of the following statements about the use of a leakage protector is true?

A:Leakage protectors can be used not only to protect personal safety, but also to supervise the ground insulation of low-voltage systems or equipment.

B:The line after the installation point of leakage protector shall not be insulated to the ground

C:In daily use, it is not allowed to press the experiment button to check whether the leakage protector is reliable

D:Protective against two-phase shock

Correct answer：

A

Question 29

What environment is it if the relative humidity of the workplace is greater than 75%?

A:Dangerous and at risk of being electrocuted

B:Not dangerous

C:General

D:Special

Correct answer：

A

Question 30

What does a red line in a single-phase three-core cable represent?

A:Zero line

B:Live line

C:Ground wire

D:Not clear

Correct answer：

B

Question 31

Leakage protector can prevent:

A:Electric shock

B:Voltage fluctuation

C:Too much electricity

D:Two-hand electric shock accident

Correct answer：

A

Question 32

What kind of safety measures does the installation of leakage protection devices belong to?

A:Basic safety measures

B:Auxiliary safety measures

C:Absolute safety measures

D:Emergency safety measures

Correct answer：

A

Question 33

How much voltage AC power is a low-voltage pen generally applicable to?

A:220

B:380

C:500

D:36

Correct answer：

C

Question 34

Which of the following is the initial cause of electrical fire?

A:The power fuse do not work.

B:Switch to electrical circuit when live.

C:Over-current operation of line or equipment

D:No protective zero or ground connection

Correct answer：

C

Question 35

Which of the following can be used to measure insulation resistance?

A:Multimeter

B:Megohmmeter

C:Oscilloscope

D:Electroprobe

Correct answer：

B

Question 36

What does it represent if the indicated voltage at the output end of the auto-transformer is zero?

A:It is safe

B:No electricity

C:It may not be safe (if the live and zero wires at the input end are not connected as required, there will be high voltage at the side of the transformer)

Correct answer：

C

Question 37

After the AC circuit is cut off, the internal capacitance may:

Correct answer：

D

Question 38

Which of the following is the initial cause of electrical fire?

A:The power fuse do not work.

B:Switch to electrical circuit when live.

C:Aging or damage of insulation

D:Indoor humidity

Correct answer：

C

Question 39

What is the main factor that affects the harm degree of electric current to human body?

A:Magnitude of the current

B:The way electricity flows through the body

C:Frequency of current and body resistance

D:All of the above

Correct answer：

D

Question 40

The color code of the five-wire system of power distribution wire U, V, W, zero, and ground wires are as follows:

A:Blue, two-color lines, yellow, green and red

B:Yellow, green, red, blue and two-color lines

C:Two-color lines, yellow, green, red and blue

D:Red, blue, two-color lines, yellow, and green

Correct answer：

B

Question 41

What adverse reaction can an operator have under a long-term high-frequency electromagnetic field?

A:Difficult breathing

B:A nervous breakdown

C:Fatigue weakness

D:Heart rate slows down

Correct answer：

C

Question 42

After the three-phase switch is closed or the three-phase air switch is closed, the three-phase motor is humming, not rotating or rotating very slowly. Why is that?

A:Short circuit

B:Open circuit

C:Lack of phase

D:Three-phase power supply symmetry

Correct answer：

C

Question 43

Which of the following extinguishers is not suitable for electrical fires?

A:Carbon dioxide fire extinguisher

B:Dry chemical fire extinguisher

C:Foam extinguisher

Correct answer：

C

Question 44

When the supply voltage is higher than the capacitance withstand voltage, it will cause:

A:Capacitor short circuit

B:Capacitor heating

C:Capacitor burst and hurt people

D:Capacitor does not burst

Correct answer：

C

Question 45

When the power transformer is short-circuited, what will happen until it burns out?

A:Power transformer smelling

B:Power transformer smoking

C:Power transformer heating

D:All of the above

Correct answer：

D

Question 46

In a circuit with resistance, capacitance, and inductance, the supply voltage is tens of volts, and the voltage of capacitance or inductance can be:

A:A few volts

B:Do not exceed the supply voltage

C:Over 100 volts

D:Wo not cause death

Correct answer：

C

Question 47

When the wire is grounded, the closer the body is to the grounding point, the higher the step voltage will be. The further the distance, the lower the step voltage. In general, how far from the grounding point can the step voltage be regarded as zero?

A:Within 10 m

B:Beyond 20 m

C:Beyond 30 m

D:Beyond 50 m

Correct answer：

B

True or False question

Question 1

A test pen can be used to check whether all kinds of power sources have electricity.

A:TRUE

B:FALSE

Correct answer：

B

Question 2

There are strong current and weak current, and weak current components such as weak current switches cannot be used in strong current circuit.

A:TRUE

B:FALSE

Correct answer：

A

Question 3

During electrical maintenance, a "No Closing, Someone Working" sign should be hanging in the distribution box or switch.

A:TRUE

B:FALSE

Correct answer：

A

Question 4

In cabling, strong and weak current can be used together with the same cable pipeline.

A:TRUE

B:FALSE

Correct answer：

B

Question 5

When using a clipper ammeter, pay attention to the range of the clipper ammeter. Wear insulation gloves when measuring, stand on an insulation mat, and do not touch other equipment, in case of short circuit or grounding.

A:TRUE

B:FALSE

Correct answer：

A

Question 6

In wet, high-temperature, or conductive dusty places, voltage supply should be reduced in experiment .

A:TRUE

B:FALSE

Correct answer：

A

Question 7

If the circuit fuse has been blown, copper wire or iron wire can be used as a substitute in a short period of time.

A:TRUE

B:FALSE

Correct answer：

B

Question 8

The switch connecting to an electrical equipment should be installed in the live wire.

A:TRUE

B:FALSE

Correct answer：

A

Question 9

It is dangerous to open the cover of an electronic instrument containing a high-voltage transformer or capacitor.

A:TRUE

B:FALSE

Correct answer：

A

Question 10

Power leads of power tools must be grounded reliably.

A:TRUE

B:FALSE

Correct answer：

A

Question 11

When connecting circuit components, the main attention should be paid to the components' withstand voltage and power.

A:TRUE

B:FALSE

Correct answer：

A

Question 12

At a place that produces static electricity easily, keep the air moist; and the staff should wear anti-static clothes and shoes.

A:TRUE

B:FALSE

Correct answer：

A

Question 13

Electromagnetic current transformer shall not open circuit when in use, and voltage transformer shall not short circuit when in use.

A:TRUE

B:FALSE

Correct answer：

A

Question 14

It is forbidden to connect wires randomly in the laboratory. To self-make non-standard equipment during the experiment, first report to the laboratory management for approval, and then ask electrical professionals to connect it safely according to the standards.

A:TRUE

B:FALSE

Correct answer：

A

Question 15

As long as the quality of the wiring boards meets the requirements, multiple wiring boards can be connected in series at will without affecting the use.

A:TRUE

B:FALSE

Correct answer：

B

Question 16

Manual power tools can be used in an environment full of combustible gas.

A:TRUE

B:FALSE

Correct answer：

B

Question 17

In inflammable, explosive, easy-to-burn, and electrostatic places, chemical fiber protective equipment can be used.

A:TRUE

B:FALSE

Correct answer：

B

Question 18

Power tools should be regularly checked and repaired.

A:TRUE

B:FALSE

Correct answer：

A

Question 19

The total electrical load connected to a wiring board must not exceed the maximum capacity of the wiring board.

A:TRUE

B:FALSE

Correct answer：

A

Question 20

In an open electrical experiment or scientific research laboratory, two or more people are required to carry out the experiment.

A:TRUE

B:FALSE

Correct answer：

A

Question 21

In order to prevent electric shock, such technical measures as insulation, protection, and isolation can be used to ensure safety.

A:TRUE

B:FALSE

Correct answer：

A

Question 22

Leakage protector does not work in case of two-phase shock (human hands touch the two-phase power supply).

A:TRUE

B:FALSE

Correct answer：

A

Question 23

A leakage protector can not only protect personal safety, but also can be used to monitor the insulation of a low-voltage system or equipment. The line after the installation point of the leakage protector shall be well insulated to the ground.

A:TRUE

B:FALSE

Correct answer：

A

Question 24

To eliminate static electricity in the pipeline relies mainly on shielding.

A:TRUE

B:FALSE

Correct answer：

B

Question 25

Fuses and air switches can effectively prevent electrical fires.

A:TRUE

B:FALSE

Correct answer：

B

Question 26

Metal materials provide excellent shielding against low-frequency magnetic fields.

A:TRUE

B:FALSE

Correct answer：

B

Question 27

Leakage protection should be installed to ensure safety when using hand-held power tools, such as a hand electric drill or an electric grinding wheel.

A:TRUE

B:FALSE

Correct answer：

A

Question 28

If someone is seriously electrocuted, we should first cut off the power supply, and then carry out emergency rescue such as artificial respiration, and immediately make an emergency call to 120.

A:TRUE

B:FALSE

Correct answer：

A

Question 29

When using hand-held or mobile power tools in places with explosion and fire hazards, we must use power tools with explosion-proof measures.

A:TRUE

B:FALSE

Correct answer：

A

Question 30

In the foot cutting procedure after the welding of the electronic circuit board, the foot cutting surface should deviate from the body, especially the face, to prevent the body from being hurt.

A:TRUE

B:FALSE

Correct answer：

A

Question 31

Electric shock is usually an accident in which a person is injured by contact with a live wire or device. In order to avoid electric shock, the equipment must be reliably grounded and the person must be insulated from the ground.

A:TRUE

B:FALSE

Correct answer：

A

Question 32

Static electricity has three characteristics: high voltage, prominent static induction, and serious tip discharge.

A:TRUE

B:FALSE

Correct answer：

A

Question 33

There are two types of electric current injury to the human body: electric shock and electric injury.

A:TRUE

B:FALSE

Correct answer：

A

Question 34

Short circuit refers to the phenomenon in which two phase lines, the phase line and the zero line or ground, touch each other without passing through the load, or the resistance is very small, resulting in the current surge in the electrical circuit.

A:TRUE

B:FALSE

Correct answer：

A

Question 35

Repeated grounding means that one or more points on the zero line are reconnected to the ground through grounding devices, which improves the safety of the line.

A:TRUE

B:FALSE

Correct answer：

A

Question 36

The basic elements of electricity safety are: ensure good electrical insulation, ensure safe distance, select proper line and socket capacity and equipment power, and do not use unbranded products.

A:TRUE

B:FALSE

Correct answer：

A

Question 37

Safety distance in high voltage experiment: 10kV: 0.7m; 66kV: 1.5 m; 220kV: 3 m.

A:TRUE

B:FALSE

Correct answer：

A

Question 38

A power frequency current of 50 milliamps can give a person a fatal shock.

A:TRUE

B:FALSE

Correct answer：

A

Question 39

The resistance file of a multimeter can be used to measure the insulation resistance.

A:TRUE

B:FALSE

Correct answer：

B

Question 40

When the circuit is resonant, the voltage of the capacitor can be several times the voltage of the supply.

A:TRUE

B:FALSE

Correct answer：

A

Question 41

The death rate of two-handed electrocution is much higher than that of one-handed electrocution.

A:TRUE

B:FALSE

Correct answer：

A

Question 42

Static electricity can cause explosions, electrical insulation, and breakdown of electronic components.

A:TRUE

B:FALSE

Correct answer：

A

Question 43

The ground line and the zero line serve the same purpose.

A:TRUE

B:FALSE

Correct answer：

B

Question 44

A short circuit can make the short-circuit area or even the entire circuit overheat, thus causing the insulation layer of the line to burn, causing fire.

A:TRUE

B:FALSE

Correct answer：

A