What does the term coulomb mean?
Resistor X is shown connected to a cell in Fig. 6.1. It is a wire with cross-sectional area $A$ and length $l$. The current in the wire is $I$. Show that the mean drift speed $v$ of the charge carriers in X is given by $v = \frac{I}{nAe}$, where $e$ is the charge on a charge carrier and $n$ is the number of charge carriers per unit volume in X.
A $12\,\text{V}$ battery with negligible internal resistance is linked to two resistors Y and Z, as shown in Fig. 6.2.
The resistors are made from wires of the same material. Wire Y has diameter $d$ and length $l$. Wire Z has diameter $2d$ and length $2l$. Find the ratio of the mean drift speed of the charge carriers in Y to the mean drift speed of the charge carriers in Z.
Show that the ratio of the resistance of Y to the resistance of Z is $2$.
Find the potential difference across Y.
Find the ratio of the power dissipated in Y to the power dissipated in Z.