A dry cell of rating 1.5 V is connected across a 5 Ω resistor. A voltmeter connected across the resistor reads 1.5 V. The same resistor is now connected to another cell whose emf is 1.3 V but the voltmeter reads only 1.2 V.
(i) Define electromotive force of a cell.
(ii) Distinguish between emf and terminal voltage of a cell with reference to the above observations.
(iii) Explain why the terminal voltage equals the emf in the first case.
(iv) Explain qualitatively why the terminal voltage is less than the emf in the second case.