180. In the circuit shown, when the external resistance is 8 ohms, the useful power delivered equals $P_1$. The internal resistance of the battery is $r = 4\ \Omega$. To what value should we change the external resistance so that the useful power delivered is again equal to $P_1$?
[Figure: A circuit with a battery of internal resistance $r = 4\ \Omega$ and an external resistor.]
p{3cm} p{3cm} p{3cm}} (1) $1$
(2) $2$
(3) $4$
(4) $6$
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\textbf{180.} In the circuit shown, when the external resistance is 8 ohms, the useful power delivered equals $P_1$. The internal resistance of the battery is $r = 4\ \Omega$. To what value should we change the external resistance so that the useful power delivered is again equal to $P_1$?
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\textit{[Figure: A circuit with a battery of internal resistance $r = 4\ \Omega$ and an external resistor.]}
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\begin{tabular}{p{3cm} p{3cm} p{3cm} p{3cm}}
(1) $1$ & (2) $2$ & (3) $4$ & (4) $6$
\end{tabular}
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\textbf{Physics} \hfill \textbf{120-C} \hfill \textbf{Page 15}
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