1.
Which device is specifically designed to prevent electrical shock?
Correct Answer
B. GFCI
Explanation
A Ground Fault Circuit Interrupter (GFCI) is a safety device that protects against electrical shock. It works by monitoring the electrical current in a circuit and quickly shutting off the power if it detects any imbalance, such as current leaking through a person. This rapid action helps prevent serious injuries from electrical shocks. GFCIs are particularly important in areas where electricity is used near water, such as bathrooms and kitchens, making them a critical component in modern electrical safety standards.
2.
What should be done to all exposed metal in the electrical circuit?
Correct Answer
A. Earthed
Explanation
All exposed metal in an electrical circuit should be earthed (or grounded). Earthing ensures that in the event of a fault, such as a short circuit, the excess electrical current has a safe path to the ground. This helps prevent electric shocks, fires, and other hazards by stabilizing the voltage levels and ensuring that any stray currents are safely discharged into the earth. Proper earthing is a critical safety measure in electrical systems, protecting both people and equipment from electrical dangers.
3.
What must you do to the power supply before working on a circuit?
Correct Answer
B. Switch off
Explanation
Before working on a circuit, you must switch off the power supply. Turning off the power ensures that no electrical current flows through the circuit while you are working on it, preventing the risk of electric shock, injury, or damage to the components. Always double-check that the power is completely off by using a voltage tester or similar device. This safety precaution is crucial to protect yourself and ensure a safe working environment when handling electrical systems.
4.
What is the accepted lethal level of shock current passing through a person?
Correct Answer
D. 50mA
Explanation
The accepted lethal level of shock current passing through a person is about 50mA (milliamperes). When current levels reach or exceed 50mA, they can cause severe injury or death by disrupting the normal functioning of the heart and other vital organs. At this level, the current can lead to ventricular fibrillation, a life-threatening condition where the heart's rhythm becomes erratic and cannot pump blood effectively. Understanding the dangers of electrical current levels is essential for ensuring safety when working with or around electricity, emphasizing the need for proper precautions and protective measures.
5.
How is electricity made at a power plant?
Correct Answer
B. Generator
Explanation
Electricity is made at a power plant by a huge generator. A generator converts mechanical energy into electrical energy through the process of electromagnetic induction. This is typically achieved by rotating a coil of wire within a magnetic field, which induces an electric current in the wire. The mechanical energy required to rotate the coil can come from various sources, such as steam turbines, water turbines, or wind turbines. Generators are essential components of power plants, enabling the large-scale production of electricity that is then transmitted to homes, businesses, and industries.
6.
What should you do to prevent accidents and injuries in the workshop?
Correct Answer
B. Follow rules
Explanation
To prevent accidents and injuries in the workshop, it is essential to follow safety rules. These rules protect individuals from potential hazards and ensure a safe working environment. Safety guidelines include wearing personal protective equipment (PPE), using tools and machinery correctly, maintaining a clean and organized workspace, and knowing emergency procedures. Adhering to these measures minimizes the risk of accidents, reduces injuries, and promotes a culture of safety. Understanding and following safety rules is crucial for ensuring everyone's well-being and productivity in the workshop.
7.
The severity of an electric shock depends more on the voltage when compared to the current.
Correct Answer
B. False
Explanation
The severity of an electric shock depends more on the current rather than the voltage. While voltage determines the potential for electric shock, it is the current that actually flows through the body and causes harm. Even a low voltage can be dangerous if there is a high current flow. Therefore, the statement that the severity of an electric shock depends more on the voltage is false.
8.
Mandatory signs are used to indicate that a specific course of action must be taken.
Correct Answer
A. True
Explanation
Mandatory signs are indeed used to indicate that a specific course of action must be taken. These signs are typically in the form of a white symbol or word on a blue background, and they are used to convey instructions or requirements that drivers or pedestrians must follow. Ignoring or disobeying these signs can result in penalties or hazards, making it important for individuals to adhere to the indicated actions.
9.
Green/Yellow wire is always considered as part of the live circuit.
Correct Answer
B. False
Explanation
The given statement is false. Green/Yellow wire is not always considered as part of the live circuit. In electrical wiring, the green/yellow wire is typically used as the protective earth wire or ground wire. It is used to provide a safe path for electrical current to flow in case of a fault or short circuit, and it is not intended to carry the live current. The live circuit is usually carried by wires of different colors, such as black or brown.
10.
Fuse is used to protect the circuit against earth leakage current.
Correct Answer
B. False
Explanation
Fuses are not used to protect the circuit against earth leakage current. Instead, they are used to protect the circuit against excessive current flow. Earth leakage current is typically protected by devices such as residual current devices (RCDs) or ground fault circuit interrupters (GFCIs).
11.
RCD stands for the residual current devices.
Correct Answer
A. True
Explanation
RCD stands for Residual Current Devices, which are electrical safety devices designed to protect against electric shock and fire hazards. They work by monitoring the flow of electric current and quickly shutting off the power if a leakage or imbalance is detected. This helps to prevent potentially dangerous situations and provides an additional layer of protection in electrical circuits. Therefore, the statement "RCD stands for the residual current devices" is true.
12.
Pin number 2 is connected to
Correct Answer
B. Live
Explanation
Pin number 2 is connected to the Live wire. In electrical systems, the Live wire carries the current from the power source to the device, while the Neutral wire completes the circuit. The Earth wire is used for safety purposes to prevent electric shocks. The Fuse is a protective device that interrupts the flow of current in case of an overload or short circuit. Therefore, based on the given options, the correct answer is Live.
13.
Pin number 4 of the plug is connected to
Correct Answer
A. Earth
Explanation
Pin number 4 of the plug is connected to Earth. The Earth pin is responsible for grounding the electrical appliance and providing a safe path for any excess electrical current to flow into the ground. This is crucial for preventing electrical shocks and ensuring the safety of the user. The Earth pin in electrical plugs and outlets serves two main purposes:
Grounding: It connects the appliance to the ground, stabilizing voltage and preventing electrical surges.
Safety: It provides a safe path for excess electrical current to flow into the ground, reducing the risk of electrical shocks and protecting users and devices.
14.
What is the function of the shaft in a screwdriver?
Correct Answer
B. To connect the head and handle
Explanation
The shaft of a screwdriver serves to connect the head (or tip) of the screwdriver to the handle. It is typically made of metal and provides the necessary length and rigidity to transfer the torque applied by the user from the handle to the screw. The shaft ensures that the force is efficiently directed to rotate the screw, enabling the user to drive or remove screws effectively. Properly understanding the function of each part of a tool, like the shaft in a screwdriver, is essential for using tools correctly and safely.
15.
The sign shown in the picture is
Correct Answer
B. Advisory
Explanation
The sign shown in the picture is likely an advisory sign. Advisory signs are used to provide guidance or suggestions to drivers about potential hazards or conditions on the road ahead. They are usually diamond-shaped with a yellow background and black symbols or text. These signs are not mandatory, but they inform drivers about specific situations or actions they should consider taking while driving.
16.
The meter shown in the picture is
Correct Answer
C. Power meter
Explanation
The meter shown in the picture is a power meter. This can be determined by analyzing the design and features of the meter, such as the presence of power measurement symbols, wattage units, and other indicators commonly found in power meters. A power meter is used to measure the electrical power consumption or generation of a device or circuit, making it the most suitable option among the given choices.
17.
Overload currents occur when
Correct Answer
D. All of the above
Explanation
Overload currents occur when equipment is overloaded, meaning it is being used beyond its capacity or rated limits. They can also occur when the installation is abused, for example, by using equipment in a way it was not intended or by subjecting it to excessive stress or misuse. Additionally, overload currents can be caused by a badly designed installation, where the electrical system is not properly designed or sized to handle the load requirements. Therefore, all of the given options contribute to the occurrence of overload currents.
18.
The shown below figure is called
Correct Answer
A. Consumer unit
Explanation
The figure shown below is called a consumer unit. A consumer unit is an electrical distribution board that controls and distributes electricity throughout a building or premises. It contains various components such as MCBs (Miniature Circuit Breakers) which protect individual circuits from overloading or short circuits, RCDs (Residual Current Devices) which provide protection against electric shocks, and LCDs (Liquid Crystal Displays) which may be used for displaying information such as power consumption or fault indicators. The consumer unit is an essential part of the electrical system in a building, ensuring safety and proper distribution of electricity.
19.
What is the difference between a fuse and a circuit breaker (CB)?
Correct Answer
B. Fuse can be used only once, but CB can be used many times.
Explanation
A fuse can be used only once because it contains a metal wire or strip that melts when too much current flows through it, breaking the circuit and stopping the flow of electricity. Once a fuse blows, it must be replaced. In contrast, a circuit breaker (CB) can be used many times. It is an automatic switch that interrupts the electrical flow when an overload or short circuit occurs. Once the problem is resolved, the circuit breaker can be reset and used again. Understanding this difference is crucial for maintaining electrical safety and ensuring proper function in electrical systems.
20.
One of the devices is not used for protection.
Correct Answer
D. Socket
Explanation
The RCD (Residual Current Device), MCB (Miniature Circuit Breaker), and Fuse are all devices used for protection in electrical circuits. They help to prevent electrical hazards such as short circuits and electrical fires. However, a socket is not typically used for protection but rather for providing an outlet for electrical devices to be plugged into. Therefore, the socket is the device in the given list that is not used for protection.
21.
Which component is used to manually control the opening and closing of an electrical circuit?
Correct Answer
B. Switch
Explanation
A switch is a component used to manually control the opening and closing of an electrical circuit. When the switch is turned on (closed), it allows electrical current to flow through the circuit. When the switch is turned off (open), it breaks the circuit, stopping the flow of electricity. Switches are essential components in many electrical devices and systems, enabling users to control the power supply easily and safely. Understanding the function of switches is fundamental in electrical engineering and everyday applications involving electrical circuits.
22.
What does the term 'IP rating' refer to in electrical installations?
Correct Answer
C. Ingress Protection
Explanation
The term 'IP rating' stands for Ingress Protection rating, which indicates the level of sealing effectiveness of electrical enclosures against intrusions such as dust, water, and other foreign bodies. The IP rating is defined by the international standard IEC 60529 and consists of two digits. The first digit represents the level of protection against solid objects, and the second digit represents the level of protection against liquids. Understanding IP ratings is crucial for selecting appropriate electrical enclosures for various environments, ensuring safety and reliability in electrical installations.
23.
What is the purpose of a cable gland in electrical installations?
Correct Answer
A. Attach and seal
Explanation
The purpose of a cable gland in electrical installations is to securely attach and seal the cable to the equipment. Cable glands provide strain relief and protect the cable from being pulled out or damaged. They also ensure a tight seal, preventing dust, dirt, and moisture from entering the equipment through the cable entry point. This helps maintain the integrity of the electrical connection and protects the equipment from environmental factors, enhancing safety and reliability in electrical installations.