PSC 151 Laboratory Activity 8 Electric Circuits I An Introduction

The Ancient Greek philosopher Thales of Miletus around 600 BC, reported that charge (or electricity) could be accumulated by rubbing fur on various substances, such as amber. The Greeks noted that the charged amber buttons could attract light objects such as hair. They also noted that if they rubbed the amber for long enough, they could even get a spark to jump. In 1600 the English scientist William Gilbert coined the modern Latin word electricus from the Greek word for "amber", which soon gave rise to the English words electric and electricity Electricity

All electrical phenomena derive from two of the particles that compose every atom: electrons, protons. The electron and the proton have an intrinsic property called electric charge.

Properties of Electrons, Protons, and Neutrons Electron: Charge = -1.6x Coulombs Mass = 9.11x kg Proton: Charge = +1.6x Coulombs Mass = 1.672x kg Neutron: Charge = 0 Mass = 1.674x kg

In solid metals, like wires, the positive charges are immobile, and only the negatively charged electrons flow in the direction opposite conventional current, Conventional current was defined early in the history of electrical science as a flow of positive charge. Electric Current: Moving Electric Charge An electric circuit is a closed path around which electric charge flows. An electric circuit consists of a source of the moving electric charge such as a battery and other devices such as a light bulb or motor. The source of moving electric charge provides electrical energy to the circuit while devices like lights and motors convert the electrical energy into other forms…light, heat, mechanical energy.

In an electric circuit there must be a complete path through which the charge can move from the source, through any external devices and return to the source. For an external device such as a light bulb to work the current must flow through that device.

In drawing electric circuits symbols are often used to represent different circuit components.