10.27: The circuit shown contrr-0 vm0cot c4scxhe ,fq,(b8ains 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 hag6p q(t io:idfd-m/ ggc-axy y9u)v ;;ve no resistance, the battery has a constant internal v)aqfi(yg;6- c9y:dd;ig xo/pgtm-u 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?