Question

How to find range ,of ammeter and voltmeter and resistance of wire using ohm's law?

Answer 1

the resistance of a given wire is easy It just needs to be connected to a voltage source .The ammeter has to be set up in series and voltmeter in parallel. Take down the readings and get the graph between V and I. See the slope it will give you the resistance of the wire! The ranges of voltmeter and ammeter are already mentioned on them thus eliminating the need to calculate them. Formula for least count of both is given by  :-  Range / No. of divisions If the range of a particular voltmeter/ ammeter isn't mentioned then multimeter can be used to find their range after completing the circuit. Range calculation is valid only when there is a need to constitute a voltmeter/ammeter from a galvanometer , if your voltmeter/ammeter is faulty and the rare case its not visible clearly! In this case, a working voltmeter with a faulty ammeter can be used and (whose range is to be determined) with a resistance whose value is known to you.  Now by using Ohm's law the current can be obtained and marked on the ammeter!