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.
Electric and magnetic fields (EMF) are invisible lines of force generated by natural phenomena such as the earthâs magnetic field or lightning. EMF are also produced by electricity and other man-made sources that we are exposed to in our daily lives like household appliances, computers and cell phones. In fact, EMF surrounds all things electrical. When electric current flows through a conductor, it produces both an electric field and a magnetic field.