A heat engine is working between the temperatures 600 K and 300K. If temperature of source is decreased by 100K, efficiency is η1  and if temperature of sink is decreased by 100 K, efficiency becomes  η2 . find  η1η2

efficiency of heat engine =η=1-T2T1;   T1,T2 temperatures of source and sink;  given T1=600K,T2=300K temperature of source is decreased by 100K, efficiency is   η1η1=T11−T2 T11=500−300500=25temperature of sink is decreased by 100 K, efficiency becomes η2   η2=T1−T21T1=600-200600=23 η1η2=25X32=35