A student gradually increases the potential difference across an unknown conductor and records a linear increase of current, producing a straight-line V–I graph that passes through the origin.
(i) Explain how the slope of this graph enables the student to determine the resistance of the conductor.
(ii) Taking an arbitrary point with coordinates (V,I) on the straight line, justify how these coordinates specify the rate at which electrical energy is being converted inside the conductor.
(iii) If the applied potential difference is doubled while the conductor remains ohmic, describe and explain the resulting change in the power dissipated, without performing a numerical calculation.