When a high resistance voltmeter is connected directly across a resister its reading is 2 V. An electric cell is sending the current of 0.4A, (measured by an ammeter) in the electric circuit in which a rheostat is also connected to vary the current.
Name and state the law applicable in the given case. A graph is drawn between a set of values of potential difference (V) across the resister and current (I) flowing through it. Show nature of graph thus obtained.
The law applicable here is Ohm’s Law.
It states that the current flowing through a conductor is directly proportional to the potential difference across the conductor
I 
V.
The proportionality constant is the resistance of the conductor; it is constant for the known range of the temperature.
V = IR.
The Graph obtained is the straight line with positive slope passing through the origin as shown in the figure below.
