Electromotive Force
When a steady current is to be passed through a resistance, a constant potential difference must be maintained across its ends.
An electric cell is a device which can maintain a constant potential difference across its ends. The cell converts its chemical energy into electrical energy and transfer its energy to the resistance connected its ends. This energy is dissipated as heat in the resistance.
The positive charge carriers in the current fall from high to low potential across resistance. The cell lifts these charges from low potential and puts them again at higher potential. This influence of the cell that makes the charge move from low potential to higher potential is known as electromotive force (EMF).
Quantitatively EMF is the potential difference across the terminals of a cell when the cell is in open circuit i.e., when it is not delivering any current.
No comments:
Post a Comment