1 comes from the electrons in an atom when they are transfered them between objects. + + electrons have a negative (-) charge

2 Static Current  Build-up of electrical charge  Electrons move in non-specific directions  Flow of electricity through wires  Electrons move in definite paths  Examples – lightning, zap from carpet when touch something, static cling in clothes and hair  Examples – anything with a cord or wire to power, hair dryer, phone, iPod

Most objects tend to be meaning that they have equal number of positive and negative charges. # of Protons = # of Electrons (positive charge) = (negative charge) =

4 Neutral Object Charged Object Net Charge: Net Charge of Objects

5 Opposite Charges Attract + - Same Charges Repel Law of Electrical Charges

Negative charges in the wall repel from the balloon. 1. Rub a balloon on a sweater to “charge it up.” The balloon sticks because the positive charges left over are attracted to the balloon. Demonstration: How do Balloons stick to walls?

7 A battery uses chemical energy to move electrical charges.

8 + Circuits flow in a circular path from positive end to negative end

9+ Light will not go on not connected no current will flow. because the wire is not connected to the battery; no current will flow.

10+ Light bulb turns on because the electrical current can now flow through the complete circuit.

11 an accidental path for current to flow often causing risk of shock or fire a branch with zero or very low resistance

12 Safety Devices Circuit breaker - piece of metal that bends when it gets over heated opening switch because current is too high Fuse - small piece of metal that melts if the current becomes too high opening switch GFI (ground fault interrupter) - usually found in bathrooms or garages shuts off plug when current if too high.

13 Wire Power Source (1.5 V) Bulb Resistance Switch+ openclosed

14 WATCH! Do you notice any difference between the wirings of the two circuits above? Series Circuits Parallel Circuits

15 Series Circuits + The light bulbs turn on. However, since the voltage drops, the lights are dimmer..75 V Battery is 1.5 V

16 + If this light bulb does not turn on, neither light bulb will turn on. This is because the circuit is broken here; so the current can’t flow to this bulb here. Burned out light bulb Battery is 1.5 V Christmas lights were commonly made this way. Series Circuits

17 Current divides and has more than one path. + Parallel Circuits

18 + The current divides because it has more than one path. Even though the path is stopped, the other light turns on because its circuit is not broken. Burned out light bulb Your house is wired with parallel circuits. Why do you think this is so? Parallel Circuits

19 … house was wired in series. What would happen if a light bulb burned out? How would you have to find out which one it was to fix?

20 Series Circuits Parallel Circuits Only 1 path for electricity to goMany paths for electricity to travel When 1 light in the path goes out, they all go out because there is no other path. When 1 light in the path goes out the electricity can find another way to transfer the current Current is the same in all points Voltage is the same at each branch because each branch is like a separate series circuit connected to a source. Voltage is reduce by each resistance added like another light bulb, heater, or appliance. Each branch does NOT always have the same current because it depends on how much resistance is in each branch. Example: Saw has more than a lamp