Electric Cells and Batteries

📚 Key Concepts

🔹 How Batteries Work

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A battery generates electric current due to chemical reactions taking place inside it.

Basic Components:

  • Electrodes – Two metal plates of different materials
  • Electrolyte – Chemical solution that conducts electricity
  • Container – Houses the electrodes and electrolyte
  • Terminals – Positive and negative connection points

🔹 Types of Electric Cells

1. Voltaic/Galvanic Cell:

  • Historical significance – First electric cell invented
  • Construction – Two different metal plates in electrolyte
  • Working – Chemical reaction produces electricity
  • Limitation – Single use, liquid electrolyte

2. Dry Cell:

  • Modern design – Most widely used today
  • Electrolyte – Thick moist paste (not liquid)
  • Construction – Zinc container + Carbon rod + Paste
  • Advantage – Portable, leak-proof
  • Limitation – Single use, must be disposed after use

3. Rechargeable Batteries:

  • Reusable – Can be charged and used multiple times
  • Cost-effective – Saves money over time
  • Environmental – Reduces waste
  • Applications – Phones, laptops, vehicles, inverters
  • Limitation – Eventually wear out after many cycles

🔹 Battery Chemistry

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Lithium-ion Batteries:

  • Most common rechargeable battery type
  • High energy density – Store more power in smaller size
  • Materials – Lithium, cobalt, and other special metals
  • Future – Solid-state batteries being developed

Metal Electrode Pairs:

  • Zinc/Copper, Iron/Copper, Aluminum/Copper
  • Different metals have different electrical properties
  • Some act as positive, others as negative electrodes

🧪 Practical Activity

🔸 Lemon Battery: Copper wire + Iron nail + Lemon juice = Electric current!

🔸 LED Test: Use multiple lemons in series to light up LED