(a)[1]
What does the ohm mean?
(b)
A $15\ \text{V}$ battery with negligible internal resistance is joined to resistors P and Q, as shown in Fig. 6.1. The resistors are made from wires of the same material. P has diameter $d$ and length $2l$. Q has diameter $2d$ and length $l$. The resistance of P is $12\ \Omega$.
(b(i))[3]
Show that Q has a resistance of $1.5\ \Omega$.
(b(ii))[3]
Calculate the combined power dissipated in resistors P and Q.
(b(iii))[3]
Calculate the ratio $\dfrac{\text{average drift speed of the charge carriers in P}}{\text{average drift speed of the charge carriers in Q}}$.
(c(iii))[3]
Calculate the ratio $\dfrac{\text{average drift speed of the charge carriers in P}}{\text{average drift speed of the charge carriers in Q}}$.