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.
Definition of EMF-an EMF or electromagnetic field is the field or area of force caused by movement of an electrical charge and containing some amount of electromagnetic energy. Definition of EMR-Electromagnetic radiation, or electromagnetic radio frequency radiation EMFR. Extremely high frequency-EHF is defined as billions of cycles per second, and is the highest radio frequency band, extending from 30 to 300 GHz. or in wavelength size, waves are 1-10 mm or millimeters, also abbreviated MMW or mmW. Microwaves are an example.