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 is EMF? We live in an invisible sea of electromagnetic field radiation. Subtle energies constantly swirl in and around our bodies, whether or not we are aware of them. Electromagnetic Fields (EMF) are energy waves with frequencies below 300 hertz or cycles per second.