The current supplied by a battery as a function of time is i(t) = (0.88 a) e^(-t*6 hr). what is the total number of electrons transported from the positive electrode to the negative electrode from the time the battery is first used until it is essentially dead?
3.7 x 10^18
5.3 x 10^23
4.4 x 10^22
1.6 x 10^19
1.2 x 10^23

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)