Electric charge and electric current
Like mass and length, electric charge also is a fundamental property of all matter. We know that matter is made up of atoms and molecules. Atoms have particles like electrons, protons and neutrons. By nature, electrons and protons have negative and positive charges respectively and neutrons do not have charge. An electric current consists of moving electric charges. Electric current is the flow of charges just like water currents are due to the flow of water molecules. Water molecules tend to flow from areas of higher gravitational potential to lower gravitational potential. Similarly, electric current ows from higher electric potential to lower electric potential. Electricity is an important source of energy in the modern times.