How is voltmeter connected in the circuit to measure potential difference between two points ?

(a) What do you understand by the term ''potential difference''? (b) What is meant by saying that the potential difference between two points is 1 volt? (c) What is the potential difference between the terminals of a battery if 250 joules of work is required to transfer 20 coulombs of charge from one terminal of battery to the other? (d) What is a voltmeter? How is a voltmeter connected in the circuit to measure the potential difference between two points. Explain with the help of a diagram. (e) State whether a voltmeter has a high resistance or a low resistance. Give reason for your answer.

How is potential difference between two points expressed?

In the given circuit, the potential difference between the points A and B is

For the circuit in find the potential difference between points a and b.