Utilization of Electrical Energy MCQ Quiz - Objective Question with Answer for Utilization of Electrical Energy - Download Free PDF

Explanation:

Nickel-Iron Cell Discharging Process

Definition: A Nickel-Iron (Ni-Fe) cell, also known as an Edison cell, is a type of rechargeable battery that utilizes nickel oxide hydroxide as the positive electrode and iron as the negative electrode. During the discharging process, chemical reactions occur at both electrodes to produce electrical energy.

Working Principle During Discharging: In a Nickel-Iron cell, the discharging process involves the following electrochemical reactions:

At the positive electrode (cathode), nickel oxide hydroxide (NiOOH) is reduced to nickel hydroxide (Ni(OH)₂):
NiOOH + H₂O + e^- → Ni(OH)₂ + OH^-

At the negative electrode (anode), iron (Fe) is oxidized to iron hydroxide (Fe(OH)₂):
Fe + 2OH^- → Fe(OH)₂ + 2e^-

These reactions result in the flow of electrons through an external circuit, generating electrical energy that can be utilized by connected devices. The overall cell reaction during discharge can be summarized as:
NiOOH + Fe + H₂O → Ni(OH)₂ + Fe(OH)₂

Applications: Nickel-Iron cells are commonly used in off-grid and renewable energy storage systems, emergency lighting, railway signaling, and other applications where long life and robustness are critical.

Correct Option Analysis:

The correct option is:

Option 2: Iron at the negative electrode is oxidized to iron oxide, and nickel at the positive electrode is reduced to nickel hydroxide.

This option correctly describes the electrochemical reactions occurring during the discharging process of a Nickel-Iron cell. Iron at the negative electrode undergoes oxidation, while nickel oxide hydroxide at the positive electrode undergoes reduction, leading to the generation of electrical energy.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: Nickel at the positive electrode is reduced to metallic nickel, and iron hydroxide at the negative electrode is oxidized.

This option is incorrect because, during the discharging process, nickel oxide hydroxide is reduced to nickel hydroxide, not metallic nickel. Additionally, iron is oxidized to iron hydroxide, not iron hydroxide being oxidized.

Option 3: Nickel hydroxide at the positive electrode is reduced to metallic nickel, and iron is oxidized at the negative electrode.

This option is incorrect because nickel hydroxide is not reduced to metallic nickel during discharging. Instead, nickel oxide hydroxide is reduced to nickel hydroxide.

Option 4: Iron at the negative electrode is reduced to metallic iron, and nickel hydroxide at the positive electrode is oxidized.

This option is incorrect because, during discharging, iron is oxidized to iron hydroxide, not reduced to metallic iron. Additionally, nickel hydroxide is not oxidized during discharging; instead, nickel oxide hydroxide is reduced to nickel hydroxide.

The correct option is 1

Concept:

Primary cell:

• A primary cell or battery is one that cannot easily be recharged after one use and is discarded following discharge.
• Most primary cells utilize electrolytes that are contained within absorbent material or a separator (i.e. no free or liquid electrolyte) and are thus termed dry cells.
• Two examples of primary cells are Daniel's cell, and. Leclanche cell.
• The cell is not used to store electrical energy in the form of chemical energy.

Explanation:

• A primary cell is a cell that is designed to be used once and discarded, not recharged with electricity, and reused like a secondary cell.
• In general, the electrochemical reaction occurring in the cell is not reversible, so these cells cannot be recharged.​

Additional InformationSecondary cell:

• A secondary cell is a type of cell that can be electrically recharged by passing current in the opposite direction of the circuit.
• One of the best examples of secondary cells is an alkaline battery.
• Energy in an alkaline battery is obtained from the interaction of zinc metal and manganese dioxide.
• These batteries live longer and have a greater energy density. 
• It converts electrical energy into chemical energy when current is passed in it (i.e. during charging), while it converts chemical energy into electrical energy when current is drawn from it (i.e., during discharging).

The correct answer is: 4) The amount of charge a battery can store and deliver over a specific time period
Explanation:

The capacity of a battery is defined as:

• The total electric charge (in ampere-hours, Ah) it can store and deliver under specified conditions (e.g., discharge rate, temperature).

• Example: A 10 Ah battery can theoretically deliver 1A for 10 hours or 2A for 5 hours.

The correct answer is option 3.

Specular reflection: The reflection of light from a smooth and shiny surface like a mirror is called specular reflection.

Key Characteristics:

• Occurs on smooth surfaces (e.g., mirrors, calm water).
• Light rays reflect in a single, predictable direction.
• Follows the law of reflection: the angle of incidence equals the angle of reflection.
• Produces clear images, like your reflection in a mirror.

Additional Information 

Other types of reflection are:
Spread reflection: Spread reflection, also known as diffuse or mixed reflection, occurs when light is reflected in a wide range of directions from a surface with imperfections, such as a rough surface or an uneven material. 
Irregular reflection: When a beam of light falls on such a surface which is not perfectly smooth and polished, such as a wall, wood paper etc. is known as irregular reflection.

Diffuse reflection: Diffuse reflection is the reflection of light from a surface such that an incident ray is reflected at many angles, rather than at just one angle as in the case of specular reflection.

Concept:

Public lighting installations are essential for ensuring visibility, safety, and security during nighttime. A key consideration in their design and implementation is not just to illuminate the area but to do so in an energy-efficient, safe, and sustainable manner.

Evaluation of Options:

Option 1: Providing adequate illumination while ensuring energy efficiency and safety –  Correct
This addresses the core objectives of public lighting: visibility, safety, cost-effectiveness, and sustainability.

Option 2: Ignoring maintenance requirements to reduce costs –  Incorrect
Neglecting maintenance can lead to frequent outages, safety hazards, and higher long-term costs.

Option 3: Focusing only on the aesthetic design of the light fixtures –  Incorrect
While aesthetics matter, public lighting must first meet functional and safety standards.

Option 4: Ensuring the lighting system operates without any protective devices –  Incorrect
Protective devices are necessary to prevent electrical hazards and ensure system longevity.

The derived SI unit of illuminance is the lux (lx).

The correct answer is Cleaning.

Key Points

Explanation:

Electroplating: This involves the process of depositing a layer of any desired metal on another material by means of electricity. In this case, the electric current is used to reduce dissolved metal cations such that they form a thin metal coating on the electrode.

• It is the process of coating the surfaces of the components with another metallic coating to achieve decorative or protective surfaces against corrosion
• The component to be plated is dipped in the electrolyte and made as a cathode as shown in the figure
• The electrolyte supplies the metal ions of materials to be deposited from the anode to the cathode

From the diagram, it is visible that the work to be coated is on the cathode.

•  Before the electroplating process, proper cleaning is done for the purpose of reduction of Dirt, Grease, and any other surface impurities.

Additional Information

• Buffing: Buffing operation is carried out after polishing with a finer abrasive to further smoothen the surface and to provide the surface with a lustrous, grainless finish
• Soldering: Soldering is the process by which metallic materials are joined with the help of another liquified metal (solder).
• Polishing: In polishing, surface irregularities are removed from the workpiece by using abrasive particles which are glued to a flexible wheel or a belt
• Electropolishing: Electropolishing is a reverse process of electroplating.

Luminous efficiency: It is also known as radiant efficiency. It is defined as the ratio of energy radiated in the form of light, produces sensation of vision to the total energy radiated out by the luminous body.

Radiant efficiency = energy radiated in the form of light / total energy radiated by the body

Lamp efficiency is measured in lumen/watt.

Important Points:

Power dissipation in a lamp,

\(P = \frac{{{V^2}}}{R}\)

Since both bulbs are rated at the same voltage, we can say that resistance of each bulb is inversely proportional to its rated power. Therefore, the resistance of 60 W bulb (R60) is greater than the resistance of 100 W (R100) bulb.

Since lamps connected in parallel, the voltage across the both bulb is same.

The power dissipated across 60 W lamp, \({P_{60}} = \frac{{{V^2}}}{{{R_{60}}}}\)

The power dissipated across 100 W lamp, \({P_{100}} = \frac{{{V^2}}}{{{R_{100}}}}\)

As R60 > R100, the power dissipated across 100 W is greater than 60 W.

Different light bulbs last for a different time period. Out of the given lamps, incandescent lamps have the shortest life span in working hours.

• Space to height ratio is the ratio of space between luminaires (S) to their height above the working plane (Hm).
• Manufacturers specify the recommended space to height ratio (SHR) for each of their luminaires.
• Typically, a recommended space to height ratio (SHR) is 1 : 2.

Electric Traction Systems:

• Electric traction is meant locomotion in which the driving (or tractive) force is obtained from electric motors. It is used in electric trains, tramcars, trolleybuses, and diesel-electric vehicles, etc.
• They involve the use of electric energy at some stage or the other.
• Examples: battery-electric drive, diesel-electric drive, railway electric locomotive fed from overhead AC supply, tramways, and trolly buses supplied with DC supply.

Railway Track Electrification System:

Direct Current Traction System:​

• In all cases, contact systems are fed from substations which are spaced 3 to 5 km for suburban lines and 40-50 km for main lines Service.
• Substation receive power from 110/132 kV, 3-phase network (or grid). At these substations, this high-voltage 3-phase supply is converted into a low-voltage single-phase supply with the help of Scott-connected or V-connected 3-phase transformers.
• Next low AC voltage is converted to the suitable DC voltage by using suitable rectifiers or converters (like rotary converter, mercury-arc rectifier, metal or semiconductor rectifiers).
• DC motors are better suited for frequent and rapid speed control than AC motors.
• DC train equipment is lighter, less costly, and more efficient than similar AC equipment.
• When operating under the same conditions, the DC train consumes less energy than a Single-phase AC train.
• The erection cost and maintenance cost of the conductor rail is less than that of a single-phase AC system.
• No electrical interference with overhead communication lines in the DC traction system.
• The only disadvantage of the DC system is the necessity of locating AC/DC conversion sub-stations at relatively short distances apart.
   

Single-Phase Low-frequency AC Traction System:

• In this system, AC voltages from 11 to 15 kV at the frequency (50 Hz), (50/2 Hz), (50/3 Hz) Hz are used.
• Electric supply is taken from the high voltage transmission lines at 50 Hz, then in addition to a step-down transformer, the substation is provided with a frequency converter.
• supply is fed to the electric locomotor via a single over-head wire (running rail providing the return path).
• A step-down transformer carried by the locomotive reduces the 15-kV voltage to 300-400 V for feeding the AC series motors.
• To overcome the low power factor and commutation problem in the AC Series motor, a low-frequency AC supply is used.
• Another advantage of employing low frequency is that it reduces telephonic interference.
• Substations are 50 to 80 km apart.
   

Three-phase Low-frequency AC System:

• It uses 3-phase induction motors which work on a 3 kV to 3.6 kV at (50/3 Hz) supply.
• Sub-stations receive power at a very high voltage from 3-phase transmission lines at the usual industrial frequency of 50 Hz.
• This high voltage is stepped down to (3 kV to 3.6 kV) by transformers and frequency is reduced from 50 Hz to (50/3 Hz) by frequency converters.
• This system employs two overhead contact wires and the track rail forming the third phase.
• Induction motors used in the system are quite simple and robust and give trouble-free operation.
• The induction motor used in this traction system has high efficiency and the ability of automatic regenerative braking.
   

Kando System (Single-phase AC to Three-phase AC):

• In this system, the single-phase 16-kV, 50 Hz supply from the sub-station is picked up by the locomotive through the single overhead contact wire.
• It is then converted into a 3-phase AC supply at the same frequency by means of phase converter equipment carried on the locomotives.
• This 3-phase supply is then fed to the 3-phase induction motors.
• Kando system is likely to be developed further.
   

Single-phase AC to DC System:

• This system combines the advantages of high-voltage AC distribution at the industrial frequency with the DC series motors traction.
• It employs an overhead 25-kV, 50-Hz supply which is stepped down by the transformer installed in the locomotive itself.
• The low-voltage AC supply is then converted into a DC supply by the rectifier which is also carried on the locomotive.
• This DC supply is finally fed to the DC series traction motor fitted between the wheels.
• The system of traction employing 25-kV, 50-Hz, 1-phase AC supply has adopted by Indian Railway.

The classification of electrical heating is shown below.