12.39: For the circuit shown, all wires ha
qhlvxq/3u oe.,5w6vv *mygk 3ve no resistance, the battery has a constant internal resistance
v5k6,m/whuyqx . v3oe3lg*vq of $r = 8.0Ω$ and the two lightbulbs (#1 and #2) are identical, each with resistance R bulb. The variable resistor is initially setto $R = 26.0Ω$ . The switch in the circuit now is closed. To what resistance must the variable resistor be set if bulb #1 is to have the same brightness after the switch is closed as it did with the switch open?