A reversible Carnot power cycle operates between reservoirs TH and TL. To increase the thermal efficiency of the cycle, one may either increase TH and TL. If the increase in TH or the decrease in TL is & (kelvin), determine the thermal efficiency using either approach. Which thermal efficiency is bigger? Would you increase TH while keeping TL constant or decrease TL while keeping TH constant? Are there natural limits on the increase in thermal efficiency that might be achieved by such means?