Active material of a lead acid cell is:

Explanation:

Active Material of a Lead Acid Cell

Definition: In a lead acid cell, the active materials are the substances that undergo electrochemical reactions to store and release electrical energy. These materials are crucial for the cell's operation, as they participate directly in the charge and discharge processes.

Correct Option Analysis:

The correct option is:

Option 1: Sponge lead

This option accurately identifies one of the primary active materials in a lead acid cell. Sponge lead, also known as porous lead, is used as the negative active material in the cell. During the discharge process, the sponge lead reacts with sulfuric acid to form lead sulfate, releasing electrical energy. During the charging process, the lead sulfate is converted back into sponge lead, allowing the cell to store energy once again.

Additional Information

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

Option 2: Semiconductor

Semiconductors are materials with electrical conductivity between that of conductors and insulators. They are used in electronic components such as diodes, transistors, and integrated circuits. However, they are not used as active materials in lead acid cells. The electrochemical reactions in a lead acid cell do not involve semiconductors.

Option 3: Resistance

Resistance is a property of materials that opposes the flow of electric current. It is not a material itself but a characteristic that can be found in various materials, such as resistors in electronic circuits. In the context of a lead acid cell, resistance is not an active material but a factor that can affect the cell's performance by causing energy losses. The active materials in a lead acid cell are those that participate in the electrochemical reactions, not materials exhibiting resistance.

Option 4: Wrought iron

Wrought iron is an iron alloy with a very low carbon content, known for its toughness, malleability, and corrosion resistance. It is used in various structural and decorative applications. However, wrought iron is not used as an active material in lead acid cells. The materials involved in the electrochemical reactions of a lead acid cell are lead, lead dioxide, and sulfuric acid, not wrought iron.

Conclusion:

Understanding the composition and function of a lead acid cell's active materials is crucial for appreciating its operation. The correct option, sponge lead, plays a vital role as the negative active material in the cell's electrochemical reactions, enabling the storage and release of electrical energy. The other options, including semiconductors, resistance, and wrought iron, do not pertain to the active materials in a lead acid cell and are unrelated to its electrochemical processes.

By correctly identifying the active materials in lead acid cells, one can better understand their functioning, applications, and limitations in various energy storage and power supply scenarios.