Experiment 2  Ohm's Law and Resistivity

Theory

Ohm's law states that the potential difference ($\Delta V$) across an ohmic resistor is directly proportional to the current ($I$). If the constant of proportionality is named the resistance ($R$), then Ohm's law can be expressed as \begin{equation} \Delta V = I\, R \label{lab2:eq:V_IR} \end{equation}

The opposition to current flow in a uniform wire depends on its material (or resistivity $\rho$) and geometry. More specifically, the resistance ($R$) of a piece of wire of length ($l$) and cross-sectional area ($A$) is given by the equation \begin{equation} R = \rho\, \frac{l}{A} \label{lab2:eq:R_rho_lA} \end{equation} Assume that Equations \ref{lab2:eq:V_IR} and \ref{lab2:eq:R_rho_lA} above are still theories, and perform experiments to support their predictions.