2 Atoms… Have neutrons, protons, and electrons. Protons are positively chargedElectrons are negatively charged
3 Electrons… Are located on the outer edges of atoms…they can be moved. A concentration of electrons in an atom creates a net negative charge.If electrons are stripped away, the atom becomes positively charged.
4 - + + + + - - + - + + + - - - + + - - - The world is filled with electrical charges: Electricity is the energy associated with charged particles-++++--+-+++---++---
5 What is this electrical potential called? Static Electricity-----+++--++
6 Static ElectricityThe build up of an electric charge on the surface of an object.The charge builds up but does not flow.Static electricity is potential energy. It does not move. It is stored.
7 Methods of Transfer…Occurs when there is a loss of static electricity due to three possible things:Friction - rubbingConduction – direct contactInduction – through an electrical field (not direct contact)
8 Visualizing Lightning Turn to page 199.Answer the following questionsWhen the warm humid air rises to meet the cold air, what causes the air masses to churn togetherWhat electrical property causes the negative charges in the cloud to be attracted to the positive charges in the ground?Why does the ground below have positive charges?
9 Electricity that moves… Current: The flow of electrons from one place to another.Measured in amperes (amps)Kinetic energy
10 How can we control currents? With circuits.Circuit: is a path for the flow of electrons. We use wires.
11 There are 2 types of currents: Direct Current (DC) – Where electrons flow in the same direction in a wire.
12 There are 2 types of currents: Alternating Current (AC) – electrons flow in different directions in a wire
13 There are 2 types of circuits: Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off.
17 Conductors vs. Insulators Conductors – material through which electric current flows easily.Insulators – materials through which electric current cannot move.
18 Examples Conductors: Insulators: Metal Water Styrofoam Rubber Plastic Paper
19 Activity Identifying Conductors and Insulators Page 208
20 What is Resistance?The opposition to the flow of an electric current, producing heat.The greater the resistance, the less current gets through.Good conductors have low resistance.Measured in ohms.
21 What Influences Resistance? Material of wire – aluminum and copper have low resistanceThickness – the thicker the wire the lower the resistanceLength – shorter wire has lower resistanceTemperature – lower temperature has lower resistance
22 What is Voltage?The measure of energy given to the charge flowing in a circuit.The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit.
23 Difference b/t Volts and Amps Example – you could say that…Amps measure how much water comes out of a hose.Volts measure how hard the water comes out of a hose.
24 Resistance = Voltage / Current Ohm’s LawResistance = Voltage / CurrentOhms = Volts / Amps
25 What is an electromagnet? Electromagnet – a magnet made from a current bearing coil of wire wrapped around an iron or steel core.
26 What is a generator?Generator – a machine that changes mechanical energy to electrical energyUsually use moving magnets to create currents in coils of wire.
27 What is a motor?Motor – a device that changes electrical energy to mechanical energy that can do work.