An electric circuit consisting of a 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each and a plug key was set up.
(i) Draw a diagram of this electric circuit to study the relation between the potential difference maintained between the points ‘X’ and ‘Y’ and the electric current flowing through XY.
(ii) Following graph was plotted between V and I values :
(i)
(ii) Since the graph is a straight line passing through the origin, so current is directly proportional to the potential difference.
Hence, the ration V/I remain constant.
From graph, when V = 1.5 volt, I = 0.6 amp
So, V/I = 1.5/0.6 = 25 Ω
For p.d. 0.8 V, 1.2v and 1.6v, the value of V/I ratio remains the same i.e., 2.5 ohm.
(iii) The resistance of the wire is equal to the ratio of potential difference applied and the current passing through it.
R = V/I = 25 Ω