College Physics (7th Edition)

$R_{1}=2ohm$ $R_{2}=6ohm$ Current will be same i.e. $I$. Joule heating is same as the power output of the resistors. $P_{1}=I^{2}R_{1}$ $P_{2}=I^{2}R_{2}$ Thus, $P_{2}=3P_{1}$ Clearly, the resistor with 6-ohm resistance will produce more Joule heating. Thus the answer is (b).