172. In the circuit below, what should the resistance $R$ be so that the output power from the source is maximized, and in this case the current $I$ equals how many amperes? [Figure: Circuit with EMF $\varepsilon = 24\,\text{V}$, internal resistance $r = 2\,\Omega$, and three resistors $6\,\Omega$, $12\,\Omega$, and $R$ connected in parallel, with current $I$ indicated] (1) zero and 12 (2) 3 and $4/8$ (3) 4 and 4 (4) 4 and $2/4$ \begin{flushright} Calculation Space \end{flushright} %% Page 14 Physics120-CPage 13
\textbf{172.} In the circuit below, what should the resistance $R$ be so that the output power from the source is maximized, and in this case the current $I$ equals how many amperes?
\textit{[Figure: Circuit with EMF $\varepsilon = 24\,\text{V}$, internal resistance $r = 2\,\Omega$, and three resistors $6\,\Omega$, $12\,\Omega$, and $R$ connected in parallel, with current $I$ indicated]}
(1) zero and 12
(2) 3 and $4/8$
(3) 4 and 4
(4) 4 and $2/4$
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