Three resistors of $2\ \Omega$, $3\ \Omega$ and $6\ \Omega$ are connected in (i) series, and (ii) parallel. Draw the arrangements of the resistors and find the equivalent resistance of each arrangement.

The chapter gives the rule for resistors in series (Section 11.6.1): 'when several resistors are joined in series, the resistance of the combination $R_s$ equals the sum of their individual resistances, $R_1, R_2, R_3$' (Eq. 11.14), and for resistors in parallel (Section 11.6.2): 'the reciprocal of the equivalent resistance of a group of resistances joined in parallel is equal to the sum of the reciprocals of the individual resistances' (Eq. 11.18). Applying these directly to $R_1=2\ \Omega$, $R_2=3\ \Omega$, $R_3=6\ \Omega$ gives $11\ \Omega$ in series and $1\ \Omega$ in parallel, consistent with the chapter's statement that series combination gives resistance greater than any individual resistance while parallel combination decreases total resistance below the smallest individual value.