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Thursday, 28 November 2013

Q.No.13.8: - Explain why the terminal potential of a battery decreases when the current drawn from it is increased?

Q.No.13.8: - Explain why the terminal potential of a battery decreases when the current drawn from it is increased?
Ans: - The terminal potential difference of a batter is
                                        IR      =        E – I.r
                                        Vt       =        E – I.r
Where,  E is the emf of the battery, r is the internal resistance of battery, and I.r is the potential difference across internal resistance.
When I increased then I.r becomes larger and terminal potential becomes small. Thus, we can say that when we draw more current from battery then its terminal potential difference will decrease.

Here is a rough example for this concept. The example of current flow is just like a water flow. Let suppose the pressure of water is just like the potential in the electrical system. The dam have a large capacity of water and suppose you are drawing more and more water from the dam and as a result water in the dam becomes low level and now it has low pressure on water to flow. Similarly when we draw more current from the battery then the terminal potential of the battery decreases just like dam pressure on water flow. I just tried to make this answer clear this is not a fit example for it but in my view you can understand something from it.

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