Humans were essentially hunters and gatherers. They had developed the use of fire. B â¦ ut they did not live a settled existence, instead following herds of animals on their migrations which were their primary source of food. Men were the hunters and responsible for the group's primary food source.
Emf - is the amount of energy of any form that is changed into electrical energy per coulomb of charge. pd - is the amount of electrical energy that is changed into other forms of energy per coulomb of charge. Sources of emf: Cell, battery (a combination of cells), solar cell, generator, dynamo, thermocouple.
What I don't get is why this charges a battery. Imagine the source Emf (to charge the battery) is 12V and it is charging a battery which is running low at 4V (compared to its normal voltage of 10V). A diagram of this set up that I have seen has nothing else in the circuit just these two Emf sources.