10-04-2017, 08:41 PM
factors on which internal resistance nd emf of the cell depends
EMF , Terminal Voltage & Internal Resistance of a Cell/Battery
An Electric Cell or Battery is a power generating device which generates an Electromotive Force in between it s two terminals. Along with the the developed EMF , an electric cell and battery also have some internal resistance , which in-tern effect s it s terminal voltage.
A detailed descriptions of these parameters of a battery and cell are given below:
Electromotive Force:
EMF of a cell or battery is the total voltage or potential difference developed between the two terminals of the cell/battery when the two terminals are in open circuit condition. Or. the EMF of a cell/battery is the potential difference built between the two terminals of the cell/battery when no current is being drawn from it. To measure the EMF of a cell/battery we can simply connect a voltmeter two the two terminals of the cell or battery.
EMF of a cell depends upon the physical and electrical properties of the electrodes and electrolytes used to build the cell and EMF of a battery depends upon the EMF of the cell , numbers of cells and the cells combination types used to build the battery.
Terminal Voltage:
Terminal Voltage of a cell or battery is the potential difference build between the two terminals of the cell/battery or load when a load is connected to the cell or battery or when a current is being drawn from the cell or battery. Due to the internal resistance of a cell/battery some EMF is used to overcome the resistance so the terminal voltage of a cell or battery is always smaller than it s EMF . The terminal voltage of a cell/battery depends on the EMF of the cell/battery , Internal resistance and the load resistance.
The difference between and EMF ( EMF) and Terminal Voltage ( V) of a cell/battery can be calculated as following:
EMF - V = I \times r
Where, I is the total current being drawn from the cell/battery and r is the internal resistance of the cell/battery.
Internal resistance:
Due to various physical and chemical constraints the electron when travelling from the negative terminal of a cell or battery to the positive terminal , experiences some resistance. This resistance experienced by an electron or current inside the cell or battery is called the internal resistance of the cell or battery. Such resistance is caused due to resistance of electrodes , deposition or extra materials in electrolytes and electrodes of a cell. Is the Internal resistance of a cell or battery which resists the flow of electron through the cell/battery and causes the Terminal Voltage to be smaller than the actual EMF of the cell/battery.
To get full information or details of factors on which internal resistance nd emf of the cell depends please have a look on the pages
http://farside.ph.utexas.edu/teaching/30...ode57.html
http://physicsnet.co.uk/a-level-physics-...esistance/
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