Ch 04 - Electricity: Magnetic and Heating Effects8th Science

A cell generates electricity through internal Redox (Reduction-Oxidation) Chemical Reactions.

• The reaction strictly occurs between two dissimilar conductive plates called electrodes and a surrounding conductive chemical fluid or paste known as the electrolyte.
• This spontaneous chemical reaction establishes a potential difference (voltage), forcing an electric current (flow of electrons) to travel from the negative terminal to the positive terminal through an external closed circuit.

The Voltaic Cell consists of three main components housed in a container:

1. Electrolyte: An ionic liquid solution (usually a weak acid, like dilute sulfuric acid, or a salt solution).
2. Positive Electrode (Anode): Typically made of Copper, which attracts electrons from the external circuit.
3. Negative Electrode (Cathode): Typically made of Zinc, which chemically dissolves into the electrolyte, releasing electrons into the external circuit.
   Limitation: It is a "Primary Cell." Once the Zinc is entirely consumed by the chemical reaction, the cell goes "dead" and cannot be recharged.

• Galvani incorrectly hypothesized that a dissected frog's leg twitched because of innate electricity generated inside the biological tissue.
• Volta's Proof: Volta replaced the biological frog leg with non-living paper soaked in saltwater (acting as an electrolyte) and sandwiched it between two different metal discs (Zinc and Copper).
• He successfully generated a measurable electric current, proving that electricity was generated purely by the chemical interaction of dissimilar metals and an electrolyte, leading directly to the invention of the Voltaic Pile (the first battery).