The document discusses the history of batteries and cells, including their key components and types. It explains that a cell consists of electrodes, electrolyte, and produces a chemical reaction. Primary cells cannot be recharged while secondary cells can be reused. The document also defines electromotive force (EMF) as the potential difference developed in an open circuit, and internal resistance as the resistance within a battery that causes a voltage drop under load. V=ε-Ir describes the relationship between these factors.

1. Cells, EMF, Internal
resistance

2. Contents
History
Cell or battery
Primary cell and secondary cell
EMF and internal resistance

3. History
• Alessandro Volta invented electric battery known as Voltaic pile.
• John Frederic Daniell - developed Daniell cell.
• George Leclanche invented Wet cell.
• Dr. Carl Gassner introduced the Dry cell battery.
• Gaston Plante introduced the first rechargeable battery.

4. Cell or battery
• A cell consists of three parts.
• Electrodes - A positive terminal and negative terminal.
• Electrolyte- a chemical solution.
• A combination of two or more cells is called battery.
• When chemical reaction takes place reduction reaction occurs at
cathode and oxidation process occurs at anode.

5. A cell

6. Primary cell and secondary cell
• A primary cell is not able to charge again and so it can be used only
once.
• It is possible to charge again in a secondary cell and thus it can be
reused again and again
• Cells can be connected both in series and parallel..

7. Batteries at home
• It is possible to make batteries at home using potato, lemon etc.
• Potato act as an electrolyte.

8. Emf and internal resistance
• Electromotive force is the potential difference developed between
the two terminals of a battery in an open circuit. ε = E/Q, where ε is
the electromotive force, E is the energy and Q is the charge.
• Internal resistance within the battery resists the current flow when
connected to a circuit and causes a voltage drop when current flows
through it.
• V = ε – Ir, where V is the potential difference across the circuit, ε is
the emf, I is the current flowing through the circuit, r is internal
resistance.

9. Emf and internal resistance

10. Hey Friend,
This was just a summary on Cells, EMF, Internal Resistance. For more
detailed information on this topic, please type the link given below or copy
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www.askiitians.com/iit-jee-electric-current/cells-emf-internal-resistance/