Question

Which of the graphs in Fig. Q25.12 best illustrates the current I in a real resistor as a function of the potential difference V across it? Explain.

Short answer

Graph (a)best illustrates the current I in a real resistor as a function of the potential difference V across it.

Because as per Ohm’s law the graph of current vs potential should be a straight line.

Step-by-step solution

Ohm’s law

The resistance, or the ratio of voltage to current, for all or part of an electric circuit at a fixed temperature, is generally constant.

Ohm's law may be expressed mathematically as

_{$\frac{\mathrm{V}}{\mathrm{I}}=\mathrm{R}$}

Understand the equation and match with the graph

Ohm’s law in an equation form is

$$\begin{gathered} \frac{\mathrm{V}}{\mathrm{I}}=\mathrm{R} \\ \mathrm{I}=\frac{\mathrm{V}}{\mathrm{R}} \end{gathered}$$

Therefore, the slope of the equation is_{$\frac{1}{\mathrm{R}}$.}

So, the graph will be in a straight line.

Therefore graph (a)best illustrates the current I in a real resistor as a function of the potential difference V across it because as per Ohm’s law the graph of current vs. potential should be a straight line.