Physics
Static electricity
electric charges build up on the surface of an object, when an object is moved close to or touches abother object the charge build up creates electric discharge, the flow of charge between two objects follows an unpredictable path, the flow of charge lasts for very short periods of time, makes it difficult for us to use
Current electricity
refers to electric charges that flow through a conductor in a controlled way, steady charge and predictable path, the controlled flow allows us to create devices that do useful work. To make the electrons move through a conductor, there needs to br a power source such as a battery or electricity from an electric generating station to create the flow of electrons
a conductor
usually made of unsulayed copper or aluminium, are used to join the circuit together together and provide a pathway for electrons to flow
series circuit
electrons flow only through one path. loads are connected in a chain, one after another in one continuous loop. when one load does not work, is unscrewed or a switch is open, the whole chain of loads stops working because electrons cannot flow
parallel circuit
electrons can flow through more than one path. Loads are connected in different branches that are connected to the energy source. When a load does not work or is unscrewed in one branch, the loads in the other branches continue to function because electrons can flow through another path
open vs closed circuit
in an open curcuit the current can not dlow from one end of the power source to the other, because there is no curren flow, and therefore the light does not turn on
short circuit
current follows the path of least resistance. Resistance is provided by the lightbulb. In this case, the lightbulb will not turn on because all the current will flow through the path with just a wire and none through the path with the lightbulb
Ohm's law
in 1827, georg ohm used a thermoscouple to discover the relationship between potential difference (V) current (I), and resistance (R). On straight lines, the bigger the slope, the higher the resistance. Slope = rise/run, slope = voltage/current
Ohms law calculation
V = I x R, I = V/R, R = V/I
V is in V
I is in Amperes (A)
R is resistance (ohm symbol)
why are parallel circuit lightbulb brighter than series
in a parallel circuit, electrons only pass through one load. Therefore they donate all their energy to making it brighter. In a series circuit, the electrons have to pass through all the loads, therefore they have to split up their energy amongst all of them.
resistance in a series circuit
as you increase the amount of loads in a series circuit, the resistance increases and current decreases
resistance in a parallel circuit
the more pathways you add, the lower the overall resistance, and the higher the overall current
resistance rule: series
RT= R1 + R2 + R3
resistance rule parallel
1/RT = 1/R1 + 1/R2 + 1/R3
Insulators
materials that do not allow electrons to move through it easily. They help us to use electricity safely and use and control it the wat we do. Readily hold onto charge. They prevent electric shocks. E.g oil, fur, silk, wool, plastic, wood, rubber, pure water, paper, glass, wax.
electrostatic series
helps you determine whether an object will become positively or negatively charged when two objects are rubbed together simultaneously. For two materials, look at their positions in the electrostatic series. The materials closer to the top will lose electrons (positively charged) and the ones closer to the bottom will gain electrons (negatively charged).
Grounding
connecting a conductor to earth's surface so that charges can flow safely to the ground. Grounding makes a charged object neutral. The earth takes excess electrons from negatively charged objects, and gives free electrons to positively charged objects.