Series and Parallel Circuits Chapter 9.1

Series Circuits “Charges with ONE path to follow” Example: Christmas Lights!

Series Circuits If there is a break in one part of the circuit ... NONE OF THE CIRCUIT WILL WORK!

Series Circuit The total voltage in a series circuit is spread across the loads: a voltage drop occurs at each load where some of the total voltage is “lost”  i.e. transferred to other forms of energy Voltage here = 4V

Series Circuit The current in any part of the series circuit is the same .... since there is only one path for the current to travel

Series Circuits Resistance reduces or slows the flow of electrons in a circuit. When more loads are added to a series circuit: the total resistance in the circuit increases the current decreases

Parallel Circuits A parallel circuit has multiple paths for current to follow. If there is a break in one part of the circuit, the current in that part of the circuit would stop.

Parallel Circuits The voltage in a parallel circuit is the same throughout.

Parallel Circuits The current in a parallel circuit is divided among the different pathways that branch off. A junction point is where a circuit (and the current!) divides into multiple paths or where multiple paths combine

Parallel Circuits When loads are added to a parallel circuit, the total resistance is decreased This occurs because more loads also means more paths and more paths creates more routes for the current to flow, which actually reduces the overall resistance This would also cause the total current to increase.

Comparing Series and Parallel Circuits Series Circuit in a DVD Player Remember in a series circuit, if one component ‘breaks’, then none of it works... If the player stops being able to read a DVD, is it necessary for the circuit component that works the picture and sound to function? No....

Comparing Series and Parallel Circuits Remember in a parallel circuit, if one component ‘breaks’, then ONLY that part stops working... Parallel Circuit in a House If the bedroom light burns out, you would NOT want the entire circuit to stop...it IS necessary for the other components to still function!

Comparing Series and Parallel Circuits Lighthouse – cells in parallel Flashlight – cells in series Batteries end to end means : ↑ voltage = ↑ current More light!! But... more current means the batteries don’t last as long and need to be replaced more often Batteries in parallel means less voltage and current is used so it: LASTS LONGER! This means it requires less maintenance which is good if you’re an out-of- the-way lighthouse...

Circuit Breakers A circuit breaker acts as a switch so it can cut off ALL power coming into the house (main circuit breaker) or... It can break the circuit so current can no longer flow through a specific (branch) circuit in your house

Circuit Breakers How does it work? Remember a house circuit is a parallel circuit with MANY loads In a parallel circuit, each additional load provides a new path which decreases total resistance and increases total current MORE CURRENT IN WIRES = MORE HEAT IN WIRES TOO MANY LOADS AND = TOO MUCH HEAT TOO MUCH CURRENT FIRE!! So...

Circuit Breakers When there is too much current (and heat!) in a circuit breaker, it causes a bimetallic strip to bend, which breaks the connection and stops the current BEFORE there is a fire... Once it’s cooled, you reset the switch and the circuit works again