4.4

Version 1 


Efficiency = Useful Eout/ Total Ein x100


Useful Eout = useful energy output  (J) 
Total Ein = total energy input (J) 
Efficiency = Efficiency (%) 


Version 2 


Efficiency = Useful Eout / Total Ein


Useful Eout = useful energy output (J) 
Total Ein = total energy input (J) 
Efficiency = Efficiency (no units; a number between 0 and 1)