10.27: The circuit shown coth+r mav-k)e )*y;gg*ozus: sntains a battery (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 no resistan 2rmcwn-k f30vji /)ufce, the battery has a constant internal resistance o u0 ffvmwj 3n)-k2c/rif $r = 8.0Ω$ 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?