A resistor has a stated value of 4Ω.
(a) Draw the expected graph of potential difference versus current for this resistor for currents ranging from 0 to 3A. Mark at least two numerical points clearly.
(b) Using the graph, find the potential difference across the resistor when the current is 2.5A.
(c) Explain what the slope of the graph represents and why it remains constant for this resistor.