What is a conductor? What is an insulator? Agenda for Tuesday Feb 22 nd 1.Electricity notes/demo All late work is due by Next Friday, March 4 th

Atoms… neutronsprotons electrons Have neutrons, protons, and electrons. positively Protons are positively charged negatively Electrons are negatively charged

Electrons… outer moved Are located on the outer edges of atoms…they can be moved. concentration negative A concentration of electrons in an atom creates a net negative charge. stripped positively If electrons are stripped away, the atom becomes positively charged.

The world is filled with electrical charges:

What is this electrical potential called? Static Electricity Static Electricity

Static Electricity build up surface The build up of an electric charge on the surface of an object. does not flow. The charge builds up but does not flow. potential energy notstored Static electricity is potential energy. It does not move. It is stored.

Static Discharge… loss Occurs when there is a loss of static electricity due to three possible things: Friction Friction - rubbing Conduction Conduction – direct contact Induction Induction – through an electrical field (not direct contact)

Electricity that moves… Current ( I ) Current ( I ): The flow of electrons from one place to another. amperes Measured in amperes (amps) Kinetic Kinetic energy

How can we control currents? circuits With circuits. Circuitpath wires Circuit: is a path for the flow of electrons. We use wires.

There are 2 types of currents: Direct Current (DC) same Direct Current (DC) – Where electrons flow in the same direction in a wire.

There are 2 types of currents: Alternating Current (AC) different Alternating Current (AC) – electrons flow in different directions in a wire

There are 2 types of circuits: Series Circuit one Series Circuit: the components are lined up along one path. all c If the circuit is broken, all components turn off

Series Circuit

There are 2 types of circuits: Parallel Circuitseveral Parallel Circuit – there are several branching paths to the components Connected side by side only the components on that branch will turn off If the circuit is broken at any one branch, only the components on that branch will turn off

Parallel Circuit

Conductors vs. Insulators Conductors easily Conductors – material through which electric current flows easily. Insulators cannot move Insulators – materials through which electric current cannot move.

Examples Conductors Conductors: – Metal – Water Insulators Insulators: – Styrofoam – Rubber – Plastic – Paper

What is current? Agenda for Wednesday Feb 23 rd 1.Ohm’s law All late work is due by Next Friday, March 4 th

Electricity that moves… Current ( I ) Current ( I ): The flow of electrons from one place to another. amperes Measured in amperes (amps)

What is Resistance? opposition The opposition to the flow of an electric current heat – Can produce heat More less More resistance, less current gets through Goodlow Good conductors have low resistance ohms Measured in ohms

What Influences Resistance? Material of wire Material of wire – aluminum and copper have low resistance Thickness Thickness – the thicker the wire the lower the resistance Length Length – shorter wire has lower resistance Temperature Temperature – lower temperature has lower resistance

Potential Difference Work that must be done against electric forces to move a unit charge from one point to another – Charges move from negative to positive – Measured in volts (V) – Car battery there is a voltage of 12 V across the negative and positive

More on Voltage? measure of energy Voltage is the measure of energy given to the charge flowing in a circuit greatergreater the force or “pressure” The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit

Difference between Volts and Amps Example – you could say that… – Ampshow much – Amps measure how much water comes out of a hose. – Voltshow hard – Volts measure how hard the water comes out of a hose.

Ohm’s Law Resistance = Voltage / Current Ohms = Volts / Amps

Practice with Ohm’s Law OhmsVoltsAmps

What is an electromagnet? Electromagnet current bearing coil iron or steel core. Electromagnet – a magnet made from a current bearing coil of wire wrapped around an iron or steel core.

What is a generator? Generator mechanicalelectrical Generator – a machine that changes mechanical energy to electrical energy moving currents Usually use moving magnets to create currents in coils of wire.

What is a motor? Motor electrical mechanical work Motor – a device that changes electrical energy to mechanical energy that can do work.