10.27: The circuit sho qs pd1*ib2en+vz5: luwn contains 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 circu8igz.2pid5/p yq3 gy pit shown, all wires have no resistance, the battery has a constant interyp p8i/2 p.gd3qy g5zinal 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?