You can pluck some values in and you'll see that as this becomes smaller and this becomes larger, that E becomes more efficient. Okay, finally, let's talk about refrigerators and air conditioners. So refrigerators and air conditioners are basically reverse heat engines. What actually happens is work is inputted so that heat can be transferred from a cold body to a hot body or energy can be transferred from a cold body to a hot body. This decreases the temperature of the system but increases the temperature of the outside. For example, in this room in the summer, if I have an air conditioner and I plug it into the outlet, the energy that goes into the air conditioner basically does work on the inside room.