10.27: The circuit shown contains a battery *wx)8w cafew- o),zve8jyy c. (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, y w4fvd nxt7o6 1yf6a)all wires have no resistance, the battery has a constant i6 tov1nf4)6 y7 fdyaxwnternal 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?