To verify OHM’s law using an Ammeter and Voltmeter
OBJECT:- To verify OHM’s law using Ammeter and Voltmeter
(A) APPARATUS REQUIRED
- Given resistance wires
- Connecting wires
OHM’S Law states that at a constant temperature, the current flowing through any conductor is directly proportional to the potential difference at its ends.
Where ‘R’ is proportionally constant known as the electrical resistance of the conductor.
The equation—(1) is identical to y=mx, which is an equation of a straight line passing through the origin with slope ‘m’. Hence, if we plot a graph ‘I’ and ‘V’ for a conductor wire, the result is a straight line passing through the origin. Then, ohm’s law is said to be verified. The slope of the straight line gives the value of resistance of the wire.
Value of 10 divisions of voltmeter=0.5mv
or, the value of 1 division of voltmeter=0.05mv
Value of 10 division of ammeter=0.5mA
or, the value of 1 division of ammeter=0.05mA
|No. of observations||Ammeter Reading(I)||Voltmeter Reading (V)|
The value of V/I is found to be sensibly constant. Also, the graph of ‘V’ against ‘I’ is found to be a straight line passing the origin. Hence, ohm’s law is verified.
- Connecting wires should be of appropriate length i.e, too long wire is not preferable.
- The length of the wire should be accurately measured.
- High current should not be passed.
- Reading should be taken carefully.
- Sensitive instruments should be used.