Question

Why voltmeter can not measure emf of cell?

Answer 1

EMF of a cell is it's over all electromotive force encapsulated in it. It is net power residing in the cell or the battery.

A voltmeter needs some power for itself to consume for measuring the emf if the cell and hence it will always indicate less emf .

It will convert the emf into the terminal potential difference of the cell which is not always equal to the emf.

Hence, As the voltmeter itself draws some power so it can't be used for measuring the emf of the cell.

Answer 2

Answer:

The terminal voltage of a cell is the potential difference between its electrodes. A voltmeter cannot be used to measure the emf of a cell because a voltmeter draws some current from the cell. To measure a cell's emf a potentiometer is used since in a potentiometer measurement no current is flowing.