Technical Subject Rme

Rigid metal conduit is allowed for wiring in hazardous locations if it is threaded and made up wrench tight with at least 5 full threads. This means that the conduit must have at least 5 complete rotations of threading to ensure a secure and tight connection. This helps to prevent any potential hazards or risks in the hazardous location.

EMF stands for electromotive force, which is the force that moves electrons from atom to atom through a closed conducting path. It is responsible for the flow of electric current in a circuit. EMF can be generated by a battery or a power source and is measured in volts.

Single conductor cable runs within buildings are generally more common than multicable runs because the splicing is easier. This means that it is simpler to connect and join single conductor cables compared to multicable runs, which require more complex splicing techniques.

In solving series-parallel circuits, it is generally recommended to reduce the circuit to its simplest form. This involves simplifying the circuit by combining resistors in series and parallel until only one equivalent resistance remains. By reducing the circuit to its simplest form, it becomes easier to analyze and calculate the total current, voltage, and power in the circuit. This simplification process allows for a more straightforward and efficient solution to the circuit.

Rheostats and potentiometers are types of variable resistors. A variable resistor is a resistor whose resistance can be adjusted manually or electronically. Rheostats and potentiometers both have a variable resistance that can be changed to control the flow of electric current. Therefore, the correct answer is b. Variable.

The term "equipment" is a general term that encompasses various components used in an electrical installation. It includes materials, fittings, devices, appliances, fixtures, and apparatus. This term is used to refer to any item that is utilized as a part of or in connection with an electrical installation. It is a broad category that covers a wide range of items and is not specific to any particular type of component or system.

Rubber gloves need to be tested to withstand high voltage before using them while working on high voltage equipment. This is crucial to ensure the safety of the person wearing the gloves. If the gloves are not tested and cannot withstand the high voltage, they may not provide adequate protection and can put the person at risk of electric shock or other injuries. Cleaning, oiling, or being brand new are not sufficient measures to ensure the gloves' ability to withstand high voltage.

A ground rod is an example of a "made" electrode because it is specifically designed and manufactured for the purpose of providing a grounding connection. It is made of a conductive material, such as copper or steel, and is driven into the ground to create a low-resistance path for electrical currents to flow into the earth. This helps to protect electrical systems and equipment from electrical faults and lightning strikes. Metallic water pipes and metal frames of buildings can also serve as grounding electrodes, but they are typically considered "natural" electrodes because they are not intentionally manufactured for grounding purposes.

Thermal relays, inverse time circuit breakers, and time delay fuses are all permitted to protect motor branch circuit conductors from overload. These devices are designed to sense excessive current flow and interrupt the circuit to prevent damage to the conductors. Thermal relays rely on the heat generated by the current to trip the relay, while inverse time circuit breakers use a combination of thermal and magnetic elements to trip the breaker. Time delay fuses have a built-in delay before they blow, allowing for temporary overloads that are common in motor starting. Therefore, all three options are suitable for protecting motor branch circuit conductors from overload.

A voltage or current that is reversed at regular intervals is called sinusoidal voltage or current. This is because sinusoidal waveforms have a characteristic pattern of oscillation where the voltage or current changes direction periodically. Direct voltage or current does not reverse, and steady state refers to a condition where the voltage or current remains constant without any changes. Therefore, only sinusoidal voltage or current fits the description given in the question.

A Wheatstone bridge is used to measure medium and high resistance. This is because a Wheatstone bridge is a circuit that is specifically designed to measure unknown resistances by comparing them to known resistances. It is most effective for measuring resistances in the medium to high range. Therefore, the correct answer is b. II & III only.

The skin effect refers to the phenomenon where the current tends to flow more on the outer surface of a conductor, especially at high frequencies. This is due to the inductive action caused by the changing magnetic field around the conductor. As a result, the current density is higher near the surface, leading to increased resistance and reduced effective cross-sectional area for current flow within the conductor. This effect is commonly observed in high-frequency applications and can have significant implications for the design and performance of electrical systems.

Flexible cords and cables should not be used to run through holes in floors. This is because flexible cords and cables are not designed to withstand the wear and tear that can occur when they are run through holes in floors. The constant movement and rubbing against the edges of the hole can cause damage to the cords and cables, increasing the risk of electrical hazards such as short circuits or exposed wires. Therefore, it is important to use appropriate wiring methods and materials that are specifically designed for running through holes in floors to ensure safety and prevent potential accidents.

A premises wiring system that is separately derived means that its power is obtained from a source, such as a transformer, that is not directly connected to the supply conductors of another system. This type of system is independent and does not rely on the main power supply, making it separate and distinct from other systems in the premises.

An autotransformer has only one coil. Unlike a traditional transformer which has separate primary and secondary coils, an autotransformer uses a single winding with a tap that allows it to function as both the primary and secondary coil. This design allows for voltage transformation and regulation, but also carries some risks as the primary and secondary circuits are not electrically isolated.

The correct answer is d. The definition of ampacity is the current in amperes a conductor can carry continuously under the conditions of use without exceeding its temperature rating. This means that ampacity refers to the maximum current that a conductor can handle without overheating or causing damage. It is an important factor in determining the appropriate size and type of conductor for a given electrical application.

When the power factor of a circuit is increased, it means that the circuit is becoming more efficient in converting electrical power into useful work. This is because a higher power factor indicates a smaller phase angle between the voltage and current waveforms. As a result, the reactive power, which represents the power that is not converted into useful work but instead circulates between the source and the load, is decreased. Therefore, the correct answer is that the reactive power is decreased when the power factor of a circuit is increased.

To determine if the raceway is truly vertical, an electrician would use a level. A level is a tool that has a bubble in a liquid-filled tube, which helps determine if a surface is perfectly horizontal or vertical. By placing the level against the raceway, the electrician can check if it is straight up and down, ensuring that it is indeed vertical.

A transformer would most likely have a 90% efficiency. This means that 90% of the electrical energy input is successfully converted into output energy, while the remaining 10% is lost as heat or other forms of energy. Transformers are designed to be highly efficient in order to minimize energy losses and maximize the effectiveness of power transmission and distribution systems.

An open circuit is a circuit that is not complete, meaning there is a break or gap in the circuit. In an open circuit, there is no continuous path for the electric current to flow. Therefore, the resistance of an open circuit is considered to be infinite because there is no flow of current and no voltage drop across the open gap.

In a 3-phase circuit, each phase is separated by 120 electrical degrees. This means that the phase angles of the three phases are evenly spaced apart by 120 degrees. This is a characteristic of a balanced 3-phase system, where the power is distributed equally among the three phases.

The correct answer is "Within 36" of outside edge of basin". This means that the wall receptacle outlet in the bathroom should be installed within 36 inches of the outside edge of the basin. This location ensures convenient access to the outlet for electrical appliances and devices that may be used in the bathroom. It also helps to prevent the need for excessive extension cords or unsafe wiring practices.

The formula to find watt hours is E x I x T, where E represents the voltage or electric potential difference in volts, I represents the current in amperes, and T represents the time in hours. This formula calculates the energy consumed or produced in a given period of time.

A relay is an electrical device that is used to control the flow of electricity in a circuit. It acts as a switch, allowing a small current to control a larger current. When the relay is activated, it turns on another circuit by completing the electrical connection between the input and output terminals. This allows the current to flow through the relay and activate the circuit it is connected to. Therefore, the function of a relay is to turn on another circuit.

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When the power factor of a circuit is increased, it means that the circuit is becoming more efficient in converting electrical power into useful work. This is because a higher power factor indicates a lower amount of reactive power in the circuit. Reactive power is the power that is not directly used to perform work, but rather to maintain the electric and magnetic fields in inductive and capacitive elements. Therefore, when the power factor is increased, the amount of reactive power is decreased.

When conductors with a higher ampacity than the overcurrent device are used, the overcurrent device itself determines the circuit rating. This means that the ampere rating or setting of the overcurrent device sets the maximum current that the circuit can handle safely. The overcurrent device acts as a protective measure to prevent excessive current flow and potential damage to the conductors and equipment. Therefore, the circuit rating is determined by the overcurrent device's specifications.

When alternating current flows through a conductor, the changing magnetic field induces eddy currents in the conductor. These eddy currents tend to flow on the outer surface of the conductor, resulting in a higher current density at the surface compared to the center. This phenomenon is known as the skin effect. The increased current density at the surface leads to increased resistance and heating of the conductor. Therefore, the skin effect causes the resistance in the conductor to increase.

A squirrel cage motor can be started at full voltage because it has a simple and robust design that allows it to handle the high starting currents. The motor's rotor consists of conductive bars or "squirrel cages" that are shorted at the ends, creating a low-resistance path for the current to flow. This design allows the motor to quickly build up torque and start rotating without the need for any additional starting devices or reduced voltage. Therefore, all designs (I, II, III, and IV) can start a squirrel cage motor at full voltage.

A one-quarter bend in a raceway is equivalent to an angle of 90 degrees.

Field magnets are used to create a magnetic field in electrical machines. Copper is commonly used for field magnets because it has good electrical conductivity. Steel is also used because it has high magnetic permeability, allowing it to efficiently conduct magnetic lines of force. Wrought iron is another material used for field magnets due to its high magnetic permeability and low coercivity, which means it can be easily magnetized and demagnetized. Therefore, all three materials (copper, steel, and wrought iron) are generally used for field magnets.

Using a chalk line is the best way to lay out a 40 foot long straight line on a floor because it allows for precision and accuracy. A chalk line consists of a string coated with chalk powder, which is stretched out and snapped against the surface to create a straight line. This method ensures that the line is straight and visible, making it easier to follow and work with. Additionally, the chalk line can be easily wiped away or erased if necessary.

The power factor of an incandescent light bulb would be unity because it has a purely resistive load. This means that the current and voltage are in phase, resulting in a power factor of 1. Unity power factor indicates that the bulb is using all the supplied power efficiently without any reactive power.

The adjustable trip coil is rated at 5 amps, but the switch needs to trip at 120 amps. To achieve this, the trip coil should be set at 3 amps. This means that when the current reaches 3 amps, the trip coil will activate and cause the switch to trip, effectively protecting the circuit from excessive current flow.

To change the rotation of a DC motor, you would reverse the connections of F1 and F2. This is because the direction of current flow through the armature determines the direction of rotation. By reversing the connections, the current flow is reversed, resulting in a change in the rotation direction of the motor.

In a motor control circuit, multiple start buttons are connected in parallel. This means that each start button is connected directly to the motor, allowing any of the buttons to start the motor independently. When any start button is pressed, it completes the circuit and energizes the motor, regardless of the state of the other start buttons. This parallel connection ensures that the motor can be started from multiple locations, providing convenience and flexibility in operation.

It is generally not good practice to supply lights and motors from the same circuit because all of the given reasons are valid. Lamps require a more stable voltage supply and operate within closer voltage limits compared to motors. Motor circuits are more prone to overloads and short circuits. When motors are started, the large starting current can cause a voltage drop on the circuit, resulting in the lights blinking or burning dim. Therefore, considering all these factors, it is generally not recommended to supply lights and motors from the same circuit.

Galvanized conduit has a finish exterior and interior of zinc. Zinc is used as a protective coating on the conduit to prevent corrosion and rusting. It acts as a barrier between the metal and the surrounding environment, prolonging the lifespan of the conduit. Zinc is known for its excellent corrosion resistance properties, making it an ideal choice for applications where the conduit may be exposed to moisture or harsh conditions.

To calculate the total kilowatt-hours consumed, we need to first convert the wattage of each bulb to kilowatts by dividing by 1000. 60 watts is equal to 0.06 kilowatts. Then, we multiply the kilowatts by the number of hours the bulbs are burning (5 hours) and the number of bulbs (25). This gives us a total energy consumption of 7.5 kilowatt-hours. Therefore, the correct answer is c. 7.5.

Flexible cords and cables need to be protected when passing through holes in covers, outlet boxes, or similar enclosures. This protection is provided by fittings (I) and bushings (II). Fittings are used to secure and connect the flexible cord or cable to the enclosure, while bushings are used to prevent the sharp edges of the hole from damaging the cord or cable. Tie wraps (III) are not mentioned as a method of protection in this context. Therefore, the correct answer is I & II only.

A fluorescent light that blinks on and off repeatedly may in time result in damage to the ballast. The ballast is responsible for regulating the electrical current flowing through the light, and the constant blinking can cause excessive stress and wear on the ballast, leading to its malfunction or damage over time.

The greater the current flow through a part of the circuit, the greater the voltage drop will be. This is because voltage drop is directly proportional to current flow according to Ohm's Law. Therefore, when the current flow is greater, there will be more resistance in the circuit, resulting in a larger voltage drop.

Electrical vaults are designed to protect electrical equipment and wiring from fire hazards. They are constructed with fire-resistant materials and must have a required fire rating to ensure the safety of the equipment. A fire rating indicates the amount of time the vault can withstand a fire without compromising its integrity. In this case, the correct answer is 3 hours, which means that the electrical vault should be able to withstand a fire for at least 3 hours before any damage occurs. This extended fire resistance allows for sufficient time to control and extinguish the fire, minimizing the risk of damage to the electrical equipment and preventing the spread of fire to other areas.

The effective (R.M.S.) voltage is equal to the peak voltage divided by the square root of 2. This can be calculated as follows: R.M.S. voltage = (peak voltage) / √2 = (100%) / √2 ≈ 70.7%. Therefore, the effective voltage is approximately 70.7% of the maximum (peak) voltage.

Electrical continuity is required by the electrical code for metallic conduit to ensure equipment grounding. This means that the metallic conduit provides a continuous path for electrical current to flow, which helps to prevent electrical shocks and protects equipment from electrical faults.

An electrical timer switch for lighting is normally connected in series with the lighting circuit being controlled. This means that the timer switch is placed in the same path as the lighting circuit, allowing it to control the flow of electricity to the lights. In a series connection, the current passes through each component in the circuit, including the timer switch, before reaching the lights. This allows the timer switch to effectively control when the lights turn on and off.

Concrete, brick, or tile are considered as being "grounded" because they have the ability to conduct electricity and provide a path for electrical currents to flow into the ground. This helps to prevent electrical shocks or damage to electrical equipment by providing a safe route for the current to dissipate. Grounded materials are commonly used in construction and electrical systems to ensure safety and proper functioning.

The minimum width of working space is 750mm. This measurement is necessary to ensure that there is enough room for individuals to comfortably and safely perform tasks without feeling cramped or restricted. It allows for proper movement and maneuverability, reducing the risk of accidents or injuries. A wider working space also provides the flexibility to accommodate various equipment or tools that may be needed for the task at hand. Therefore, 750mm is the minimum width required to create an efficient and ergonomic working environment.

If the fuse blows again after replacing it with a new 20 amp fuse, it suggests that there is a problem within the circuit that is causing an excessive amount of current to flow. The electrician should check the circuit for any potential issues such as short circuits, overloaded circuits, or faulty wiring. This will help identify and rectify the problem, ensuring that the fuse does not blow again when the switch is turned on.

To remove the rough edges on both ends of the conduit after cutting, the conduit ends should be burnished. Burnishing is a process of smoothing and polishing a surface by applying pressure and friction. This technique helps to create a smooth and even finish on the conduit ends, ensuring that there are no sharp or jagged edges that could cause injury or damage to the wires or cables that will be inserted into the conduit.

The term "not readily accessible to persons unless special means for access are used" indicates that something is separated or secluded from easy reach. "Isolated" fits this description as it means being alone or separated from others.

Copper conductors are sometimes coated or tinned to help prevent chemical reactions. Copper is susceptible to corrosion and oxidation, which can lead to a decrease in conductivity and overall performance. By coating the copper conductors with tin, it creates a barrier that prevents direct contact with the environment, reducing the likelihood of chemical reactions and preserving the integrity of the conductors.

Toggle bolts/rawl plugs are the most suitable option for fastening a box to a terra cotta wall. Wooden plugs are not commonly used for this purpose, as they may not provide enough strength and stability. Lag bolts are typically used for heavy-duty applications, such as securing large objects to walls or floors. Expansion bolts are commonly used in concrete or masonry walls, but may not be suitable for terra cotta walls. Toggle bolts/rawl plugs are specifically designed for hollow materials like drywall or plasterboard, making them the best choice for securely attaching a box to a terra cotta wall.

A braking system for an electric motor can include all three options mentioned in the answer: I) Friction braking, II) Plugging, and III) Dynamic braking. Friction braking involves using friction between two surfaces to slow down or stop the motor. Plugging refers to reversing the motor's direction of rotation to slow it down. Dynamic braking uses the motor's own momentum to generate braking force by converting it into electrical energy. Therefore, all three options can be used as braking systems for an electric motor.

Bonding refers to the permanent joining of metallic parts to form an electrically conductive path. This ensures electrical continuity and the ability to safely conduct any current that may be imposed. It is an essential process in various industries, such as electrical and automotive, where the secure connection of metal components is crucial for proper functioning and safety.

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The resistor that will consume the most power is the 12Ω resistor. This is because power is equal to the square of the current passing through the resistor multiplied by the resistance. Since the current is the same for all resistors in a series circuit, the resistor with the highest resistance will have the highest power consumption.

To correct a low power factor, an electrician in the industry would first check the inductive load. Inductive loads, such as motors and transformers, can cause a lagging power factor, which means that the current lags behind the voltage. By checking and possibly adjusting the inductive load, the electrician can improve the power factor and make the electrical system more efficient.

The voltage per turn of the primary of a transformer is the same as the voltage per turn of the secondary. This is because the turns ratio of a transformer determines the voltage ratio between the primary and secondary coils. The voltage per turn is constant for both coils, so if the turns ratio is 1:1, the voltage per turn will be the same for both the primary and secondary.

A universal motor is a type of electric motor that can operate on both AC and DC power sources. It has brushes that ride on the commutator. The commutator is a rotary electrical switch that periodically reverses the direction of the current in the motor windings. This reversal of current allows the motor to continuously rotate in the same direction. The brushes make contact with the commutator, allowing the current to flow through the windings and create the magnetic field necessary for motor operation. Therefore, the correct answer is a. Commutator.

When a 240-volt heater is used on 120 volts, the amount of heat produced will be ¼ as much. This is because the heat produced by a heater is directly proportional to the square of the voltage. Therefore, if the voltage is halved (from 240 to 120 volts), the amount of heat produced will be reduced by a factor of ¼.

Electrical current is measured in terms of "electron passing point per second" because current is the flow of electric charges, specifically electrons, through a conductor. The unit for measuring current is the ampere (A), which represents the number of electrons passing through a point in a circuit per second. This measurement quantifies the rate at which electric charges are moving and is essential for understanding and analyzing electrical circuits.

A fixture that weighs more than 50 pounds should be supported independently of the outlet box. This means that the fixture should not rely solely on the outlet box for support, as it may not be able to bear the weight of the fixture. The additional support ensures the safety and stability of the fixture, preventing any potential accidents or damage.

The minimum entrance dimension for working space under 1000V is 600mm x 2000mm. This means that the entrance must have a width of 600mm and a height of 2000mm in order to provide enough space for safe access and maneuverability in the area.

Impregnated paper has the highest electrical breakdown strength and longest life over all other materials used for insulation. This means that it is able to withstand higher voltages without breaking down and has a longer lifespan compared to rubber insulation, woven cloth, and thermoplastic.

Voltage in a generator is produced by cutting lines of force. This is known as electromagnetic induction, where a conductor cuts through magnetic lines of force, creating a voltage or electromotive force (EMF) in the conductor. This phenomenon is the basis of how generators work, where a rotating coil cuts through magnetic lines of force produced by a magnet, generating an alternating current.

The transferring of electrons from one material to another refers to the phenomenon of static electricity. Static electricity occurs when there is an imbalance of electric charges on the surface of objects, causing the transfer of electrons. This can happen through friction, contact, or induction. Electrochemistry, solar electricity, and piezoelectricity involve different processes and mechanisms for the generation or transfer of electric charges, but they are not specifically related to the transferring of electrons between materials.

The given question asks for the total of the given numbers. To find the total, we need to add up all the numbers. Adding 8 5/8”, 6 ¼”, 7 3/16”, and 5 ¼” gives us 27 5/16”.

The given correct answer states that one of the disadvantages of indenter or crimp connectors is that special tools are required to make the joint. This means that using these connectors requires additional equipment, which can be inconvenient and may increase the overall cost. It implies that without these special tools, it would not be possible to properly make the joint using indenter or crimp connectors.

The Wheatstone bridge method is used for accurate measurements of resistance. This method involves the use of a bridge circuit, which consists of four resistors and a power source. By adjusting the values of the resistors, the bridge can be balanced, indicating that the resistance being measured is equal to a known resistance. This method is commonly used in various applications, such as strain gauge measurements and determining unknown resistance values in electronic circuits.

RA 7920, also known as the Philippine Ocular Drug Act, was approved on February 24, 1995. This law regulates the sale, distribution, and use of ocular drugs in the Philippines.

Circuits are grounded to limit excess voltage to ground, which might occur from lightning or exposure to other higher voltage sources. Grounding helps to protect electrical equipment and prevent damage or injury from electrical surges. It provides a safe path for the excess voltage to dissipate into the ground, reducing the risk of electrical shocks or fires.

Flux is used in soldering to keep the surface clean. When soldering, the flux removes any oxidation or impurities from the surface of the joint, ensuring that the solder adheres properly and forms a strong bond. By keeping the surface clean, the flux helps to create a reliable and durable connection between the solder and the joint.

AC voltages can be easily changed in magnitude, which makes it more versatile and suitable for various applications. This allows for efficient transmission of electricity over long distances and the ability to step up or step down the voltage as needed. In contrast, DC voltage cannot be easily changed in magnitude, limiting its use in certain applications. DC motors also have speed control, so option b is not a valid reason for preferring AC over DC. Option a is incorrect because DC voltage can be used for domestic appliances with the help of inverters. Option d is incorrect because high-voltage AC transmission can actually be more efficient than DC transmission.

Resistance causes the most power to be dissipated in the form of heat because it is directly proportional to the square of the current flowing through it. When current flows through a resistor, it encounters resistance, which causes energy to be converted into heat. This heat dissipation is proportional to the square of the current, making resistance the most efficient way to convert electrical energy into heat. In contrast, XL and XC are reactive components that do not dissipate power as heat, and resonance is a condition where the reactive components cancel each other out, resulting in minimal power dissipation.

The service-entrance conductors are the conductors that connect the service equipment to a point outside the building where they are joined by a tap or splice to the service drop. These conductors are responsible for carrying the electrical power from the utility's distribution system to the building's service equipment. They are typically installed in conduit or overhead lines and are sized based on the electrical load requirements of the building.

The resistor with the lowest resistance will consume the most power. In a parallel circuit, the power consumed by each resistor is inversely proportional to its resistance. Therefore, the 3Ω resistor, having the lowest resistance among the given options, will consume the most power.

A 3-hour fire resistant wall is typically a wall that can withstand fire for a duration of 3 hours without collapsing or allowing fire to pass through. In order to achieve this level of fire resistance, the wall needs to be constructed with materials that have high fire resistance properties. Concrete is a commonly used material for fire resistant walls due to its ability to withstand high temperatures. A thickness of 150mm is generally considered sufficient to provide the necessary fire resistance for a 3-hour fire resistant wall.

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Alternating current is not suitable for charging batteries because batteries require direct current (DC) to be charged. Alternating current continuously changes direction, whereas batteries require a constant flow of current in one direction to charge properly.

The size of the lay-in manhole for operating at 1000v, nominal or less, is 559mm x 559mm.

Conductors should not be installed in locations where the operating temperature exceeds that specified for the type of insulation used. Insulation is a crucial component in electrical systems as it provides protection and prevents the flow of electricity to unintended paths. If the operating temperature exceeds the specified limit, the insulation may deteriorate, leading to insulation failure, which can cause short circuits, electrical fires, or other hazards. Therefore, it is important to ensure that conductors are installed in locations where the operating temperature does not exceed the specified limit for the insulation type being used.

To adjust the voltage generated by a constant speed DC generator, you would change the field current. The field current determines the strength of the magnetic field in the generator, which in turn affects the voltage output. By increasing or decreasing the field current, you can adjust the voltage generated by the generator.

The normal rotation of an induction motor is counter clockwise when facing the front of the motor.

Reactance is a property of an electrical circuit that resists the flow of alternating current (AC). Unlike resistance, which affects both AC and direct current (DC), reactance only comes into play when AC current flows. Reactance is caused by the presence of inductance or capacitance in the circuit, which can cause the current to vary in response to changes in voltage. Therefore, the correct answer is that reactance will cause the current in a circuit to vary only when AC current flows.

Capacitance is the correct answer because it refers to the ability of a circuit to store electrical energy in an electric field. Capacitors, which are used in circuits to store and release electrical energy, rely on capacitance. Inductance, on the other hand, refers to the ability of a circuit to store energy in a magnetic field, while resistance refers to the opposition to the flow of electrical current. Susceptance is not directly related to the storage of electrical energy.

Unity power factor means that the current and voltage are in phase with each other. This occurs when the load is purely resistive, meaning there is no reactive component (such as inductance or capacitance) present in the circuit. In this case, the power factor is equal to 1.0, indicating that the current is in perfect alignment with the voltage.

Option I only is the correct answer because a wattmeter is a device used to measure the power consumption in a circuit, which is measured in watts. Option II and III are incorrect because they do not specify any meter that can measure power consumption.

The efficiency of electrical equipment is determined by the ratio of power output to power input. This ratio represents how effectively the equipment converts input power into useful output power. A higher value indicates a more efficient device, as it is able to minimize power losses and maximize the output for a given input. Therefore, option d, which states that the efficiency is determined by the power output divided by the input, is the correct answer.

In interior stairways where the difference between floor levels is six steps or more, lighting outlets are required to be installed. At each floor level, there should be a wall switch to control the lighting. This ensures that there is adequate lighting in the stairway for safety purposes, allowing individuals to see the steps clearly and navigate the stairs safely.

Motors are typically designed to operate in a maximum ambient temperature of 40°C unless they are specifically designed for higher temperatures. This means that if the ambient temperature exceeds 40°C, the motor may not be able to function properly or efficiently. It is important to consider the ambient temperature when selecting and using motors to ensure their optimal performance and longevity.

The turns ratio of a transformer is equal to the ratio of the number of turns on the primary coil to the number of turns on the secondary coil. In this case, the primary voltage is 120v and the secondary voltage is 480v, which means the turns ratio is 480/120 = 4. Since there are 40 turns on the primary, the number of turns on the secondary can be calculated by multiplying the turns ratio by the number of turns on the primary: 4 * 40 = 160 turns.

The correct answer is c. Only a neutral carries unbalanced current. This means that the neutral conductor is responsible for carrying any excess or unbalanced current in a circuit. In contrast, the grounded conductor is connected to the ground and is used for safety purposes, such as providing a return path for fault currents.