10.27: The circuit shown contains a batomrgcm9ky m ,y 6gu0.4tery (of emf $V_bat$) with an internal resistance r connected to a rheostat (variable resistor). When the resistance of the rheostat is increased, which of the following statements is true?

  12.39: For the circuit shown, all wires have n-2a+kvb snk b*nocc r2:nox++o resistance, the battery has a coa cx2+bbv2++ s-kc kn*n:noo rnstant internal resistance 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?