ELECTRIC CIRCUITS

Electric Circuits What is an electric circuit? SO EASY! A circuit is a loop of wire with its ends connected to an energy source such as a cell or a battery.

Circuit Basics One end of the wire is connected to the positive terminal; the other end of the wire is connected to the negative terminal. The wire is connected in this way so a current can flow through it.

Series Circuits Parallel Circuits The defining property of series circuits is that all their components (lamps, cells, switches, etc.) are connected in one loop of wire Because it has only one circuit, a series circuit has just one current A parallel circuit is like two or more series circuits connected to the same energy source The components lie inside "parallel" loops connected to the same energy source.

Simple Circuit Parallel Circuit There advantage to having a parallel circuit over a simple circuit is that a failure of one component of a parallel circuit does not lead to the failure of the other components because a parallel circuit consists of more than one loop and has to fail in more than one place before the other components fail

Circuit Symbols ammeter cell fuse battery of two cells diode lamp lamp (old) switch (open) switch (closed) voltmeter variable resistor thermistor

Ωhm’s ζαψς Ohm’s Law expresses the relationship between voltage, resistance and current is expressed in Ohm's Law : V = IR (Voltage = Current × Resistance ) Current is directly proportional to voltage for a metal conductor at a constant temperature, so if the voltage goes up, so will the current

Resistance & Resistors Although we may not usually notice it, we are always subject to resistance To understand resistance, try to imagine the difference between walking normally and walking in a pool It's the same for a current moving through a conductor

Conductors All conductors offer resistance to the flow of current. This resistance is determined by the conductor's atoms In conductors, atoms offer negligible resistance to an electric current because a significant proportion of their electrons are free to move from atom to atom. Silver and Copper are examples of good conductors

Insulators The atoms of insulators offer very considerable resistance to an electric current because a significant proportion of their electrons are not free to move from atom to atom A conductor's length, temperature, and cross- sectional area also affects its resistance Glass and synthetic polymers are examples of good insulators

THE END! By Alex Chang and Dan Stathatos