A battery converts___________

Question

Examoogle · Accepted Answer

Chemical energy to electrical energy

Explanation: A battery is an electrochemical device that converts stored chemical energy into electrical energy through redox (reduction-oxidation) reactions. During discharge, the chemical potential energy of the active materials in the electrodes is released as electrons, creating a potential difference across the terminals.

Working Principle: The principle relies on the movement of electrons between the anode and cathode through an external circuit. At the anode, oxidation occurs (loss of electrons), while at the cathode, reduction occurs (gain of electrons). This migration of charge carriers creates a DC voltage defined by the Gibbs free energy change of the chemical reaction.

Key Formulas: $\Delta G = -nFE$ — where $\Delta G$ is the change in Gibbs free energy, $n$ is the number of moles of electrons, $F$ is Faraday's constant, and $E$ is the EMF of the cell.

Key Points: Primary cells use irreversible chemical reactions to produce electricity.; Secondary cells (rechargeable) allow the chemical reaction to be reversed by applying an external voltage.; A battery is a collection of one or more electrochemical cells.; The internal resistance $r$ of a battery causes a voltage drop $V = E - Ir$ under load.

Advantages: Portable and convenient source of DC power.; Provides a stable voltage output compared to fluctuating AC supplies.

Disadvantages: Limited capacity and service life.; Potential for chemical leakage or thermal runaway if misused.

Applications: Portable electronic devices (smartphones, laptops).; Electric vehicles and renewable energy storage systems.

Additional Info: The process of reversing the energy conversion (Electrical to Chemical) is known as 'charging'.. Option A represents the charging process, not the fundamental function of a battery delivering power.

Answer: B is correct — A battery acts as a transducer that transforms chemical potential energy into electrical energy via spontaneous electrochemical reactions.

Exam Tip: In competitive exams, remember that a generator converts Mechanical to Electrical, while a motor converts Electrical to Mechanical; always distinguish these from electrochemical devices.

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