Cells and Batteries MCQ Quiz - Objective Question with Answer for Cells and Batteries - Download Free PDF

Series connection:

• Increases output voltage.
• Capacity remains the same (measured in ampere-hours).

Parallel Connection:

In order to increase the ampere-hour rating of a battery, cells are connected in parallel.

This is explained with the help of the following diagram:

• The positive terminals of all batteries are connected together, or to a common conductor, and all negative terminals are connected in the same manner.
• The final voltage remains unchanged while the capacity of the assembly is the sum of the capacities of the individual batteries of this connection.

Dry cell

• A dry cell is an electrochemical cell that converts chemical energy into electrical energy. Unlike wet cells, which use a liquid electrolyte, dry cells use a paste or gel-like electrolyte, making them portable and less prone to leakage.
• The central terminal of a dry cell is the positive terminal or cathode.
• The central terminal, or the carbon rod, is located in the middle of the dry cell and is surrounded by an electrolyte paste that facilitates the electrochemical reaction to generate electricity.

Structure of a Dry Cell

A dry cell typically consists of:

• A zinc container that serves as the negative terminal (anode).
• A central carbon rod serves as the positive terminal (cathode).
• Electrolyte: A paste made of ammonium chloride (NH₄Cl) or zinc chloride (ZnCl₂), which facilitates the flow of ions between the anode and the cathode.
• Depolarizer: Manganese dioxide (MnO₂), which helps in reducing the buildup of hydrogen gas around the cathode, thereby preventing the polarization of the cell.
• Separator: A porous material that separates the anode and the cathode, allowing ionic flow while preventing direct contact.

The correct answer is option 2.

Alkaline Cell

• Alkaline batteries are disposable batteries with electrodes made of zinc and manganese dioxide.
• Potassium or sodium hydroxide is the alkaline electrolyte used.
• An alkaline battery is a type of primary battery where the electrolyte (most commonly potassium hydroxide) has a pH value above 7.
• Typically these batteries derive energy from the reaction between zinc metal and manganese dioxide, nickel, and cadmium, or nickel and hydrogen Alkaline battery.
• The voltage generated by an alkaline cell used in a wall clock is 1.5 V

Lead-Acid cells

• ​Lead acid cells are rechargeable batteries.
• The chemical reactions that occur in lead-acid cells are reversible in nature, hence also known as secondary batteries.
• In a lead-acid battery, the anode is made of lead dioxide, and the cathode is made of metallic lead.
• The two electrodes are separated by an electrolyte of dilute sulfuric acid (a mixture of water and sulphuric acid).

Connection of cells

1.) Series connection

The current remains the same and the total current in the connection is equal to the current through each cell.

The total voltage across the combination is the sum of the voltage across each cell, hence the voltage increases.

2.) Parallel connection

The voltage remains the same and the total voltage across the connection is equal to the voltage across each cell.

The total current across the combination is the sum of the current across each cell, hence the current increases.

• A battery charger is a DC power supply source. Here a transformer is used to step down the AC mains input voltage to the required level as per the rating of the transformer.
• This transformer is always a high-power type and is able to produce a high current output as required by most lead-acid batteries.
• A bridge rectifier configuration is used to rectify the low voltage AC into DC i.e. Rectifier is a device that converts AC into DC and is further smoothed by a high-value electrolytic capacitor.
• This DC is fed to an electronic circuit which regulates the voltage into a constant level and is applied to the battery under charge, where the energy is stored through an internal process of the chemical reaction.
• In automatic battery chargers, a voltage sensor circuit is incorporated to sense the voltage of the battery undercharges. The charger is automatically switched OFF when the battery voltage reaches the required optimum level.
• Chopper is used to convert fixed dc to variable dc.
• Cyclo-convertor is a device that converts AC power at one frequency into AC power of adjustable but lower frequency without any DC current or DC stage in between.

• The method of charging a battery employs a transformer, bridge rectifier circuit, and ammeter.
• The transformer is used to step down voltage know as a step-down transformer.
• While bridge rectifier converts AC to DC which is used to charge the battery.
• This charging method is known as a rectifier battery charging method.

• Lithium-ion type of cell used for building a laptop battery pack and in mobile phones.
• The lead-acid batteries are used in vehicles.
• Zinc silver oxide batteries are used in watches, calculators, photoelectric exposure devices, hearing aids, and electronic instruments.
• Nickel-cadmium batteries are used in portable power tools, photography equipment, flashlights, emergency lighting, hobby R/C, and portable electronic devices.

Concept:

Ah Efficiency (η) = (Output ah)/(input ah)

Calculation:

Output ah = 4 × 12 = 48 ah

Input ah = 3 × 20 = 60 ah

Ah Efficiency (η) = 48/60 = 0.8

η% = 0.8 × 100 = 80%

Concept

The capacity of the battery is measured in ampere-hours (Ah).

Ah = I × t

where, Ah = Capacity of battery 

I = Current

t = Time

In an ideal case, the charging current is 10% of the total Ah of the battery.

Explanation

Given the capacity of the battery = 200 Ah

Charging current = 10% of 200

Charging current = 0.1 × 200

Charging current = 20 A

• Boost charging involves a high current for short period of time to charge the battery.
• It is generally used when the battery has been discharged heavily.
• Boost charge is given to a battery in danger of becoming over-discharged during a working shift

• A dry cell uses a paste electrolyte, with only enough moisture to allow current to flow. Unlike a wet cell, a dry cell can operate in any orientation without spilling, as it contains no free liquid, making it suitable for portable equipment.
• A common dry cell is a zinc-carbon battery, sometimes called the dry Leclanché cell, with a nominal voltage of 1.5 volts, same as the alkaline battery (since both use the same zinc–manganese dioxide combination).
• A standard dry cell comprises a zinc anode, usually in the form of a cylindrical pot, with a carbon cathode in the form of a central rod.
• The electrolyte is ammonium chloride in the form of a paste next to the zinc anode.
• The remaining space between the electrolyte and carbon cathode is taken up by a second paste consisting of ammonium chloride and manganese dioxide, the latter acting as a depolariser.
• In some designs, the ammonium chloride is replaced by zinc chloride.

• The constant voltage charging is more rapid than the constant current charging. The time of charge in a constant voltage system as compared to the constant current system is almost reduced to half.
• The current control mode is used for constant battery charging.
• The constant current charging is more efficient than the consonant voltage charging as in case of constant voltage charging the charging current may be excessive which causes heating of the battery during charging.
• The practical charging method uses two types of sources. The constant current charging at the starting where the battery is relatively empty.
• Once the battery reaches a certain voltage near the maximum voltage the battery then constant voltage charging is accomplished.