12.39: For the circuit shown, all wires have no resist
bwt9-df enzi j86 /7noaehz 3:ance, the battery has a constant internal resista
id zz- /9: ab6e37onnj tehw8fnce 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?