An ideal heat engine operates in a cycle and produces work as a result of heat transfer from a thermal reservoir at an elevated temperature th and by rejecting energy to a thermal sink at tc. the efficiency for such an ideal cycle, termed a ‘‘carnot cycle,’’ is : η = 1 - (tc/th) determine the required uncertainty in the measurement of temperature to yield an uncertainty in efficiency of 1%. assume errors are uncorrelated. use th= 1000 k and tc=300 k.