Two students P and Q perform an experiment to verify Ohm's law for a conductor with resistance R . They use a current source and a voltmeter with least counts of 0.1 ~mA and 0.1 mV , respectively. The plots of the variation of voltage drop ( V ) across R with current (I) for both are shown below The statement which is most likely to be correct is:

Step-by-step solution

For student P: Data points are scattered irregularly around the straight line → random errors present. Also, the line does not pass exactly through the origin (expected for Ohm’s law) → systematic error present. For student Q: Data points lie almost exactly on a straight line with very small scatter → negligible random error, and systematic shift is absent. Hence, P has both random and systematic errors → correct option is (4).