For a metallic resistor P, the V–I graph is a straight line through the origin that passes through the point (3.0 V, 1.0 A).
(i) Determine the resistance of P.
(ii) A second device Q shows the following readings: at 2 V, I = 0.5 A; at 4 V, I = 0.9 A. Does Q obey Ohm’s law? Give a reason.
(iii) Using your answer in (i), estimate the potential difference required to make a current of 2.5 A flow through P.