Question

(a) What do you understand by the term "potential difference" ?
(b) What is meant by saying that the potential difference between two points is $1volt?$
(c) What is the potential difference between the terminals of battery if $250joules$ 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.

Answer 1

(a) Potential difference between two points in an electric circuit is defined as the amount of work done in moving a unit charge from one.

(b) The potential difference between two points is $1volt$ means $1joule$ of work is done in moving $1coulomb$ of electric charge from one point to the other.

(c) Given : Work done $=250J,$

Charge moved $=20C.$
we know that ,

Potential difference = Work done / Charge moved
$=250/20=12.5$

(d) A voltmeter is a device which is used to measure the potential difference between two points in an electric circuit. Voltmeter is always connected in parallel across the two points where the potential difference is to be measured.

(e) Voltmeter has a high resistance so that it takes a negligible current from the circuit.