the emf of a cell is always greater than its terminal voltage.why?give reason.
EMF is the potential difference across the two terminals of a voltage source when it is not connected to any circuit. Once it is connected to a circuit, the voltage reduces slightly because of the internal resistance of the voltage source. The terminal voltage of the voltage source is the potential difference across the terminals when it is connected to a circuit. This is why the terminal voltage is always less than the EMF of the same voltage source.