Answer the following questions related to electric potential difference and the work done in transferring charge.
(i) Define electric potential difference between two points in an electric circuit.
(ii) State how a voltmeter is connected in a circuit to measure potential difference and give a reason for your answer.
(iii) Two identical positive charges are transferred one after the other between the same two points that are maintained at a fixed potential difference. Without using any numerical values, explain how the total work done in transferring both charges compares with the work done in transferring only one charge.