Electricity & Magnetism Static, Currents, Circuits Magnetic Fields & Electro Magnets Motors & Generators

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

Electrons… Are located on the outer edges of atoms…they can be moved. Are located on the outer edges of atoms…they can be moved. A concentration of electrons in an atom creates a net negative charge. A concentration of electrons in an atom creates a net negative charge. If electrons are stripped away, the atom becomes positively charged. 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 The build up of an electric charge on the surface of an object. The build up of an electric charge on the surface of an object. The charge builds up but does not flow. The charge builds up but does not flow. Static electricity is potential energy. It does not move. It is stored. Static electricity is potential energy. It does not move. It is stored.

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

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

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

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

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

There are 2 types of circuits:

Series Circuit

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. Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off.

Series Circuit

Parallel Circuit

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

Parallel Circuit

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

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

What is Resistance? The opposition to the flow of an electric current. The opposition to the flow of an electric current. The greater the resistance, the less current gets through. The greater the resistance, the less current gets through. Good conductors have low resistance. Good conductors have low resistance. Measured in ohms. Measured in ohms.

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

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

Difference b/t Volts and Amps Example – you could say that… Example – you could say that… Amps measure how much water comes out of a hose. Amps measure how much water comes out of a hose. Volts measure how hard the water comes out of a hose. Volts measure how hard the water comes out of a hose.

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

Practice with Ohm’s Law OhmsVoltsAmps

MAGNETISM Invisible force of “push” or “pull” by an object with this property In most materials and atoms, each electron is going its own way But in a magnet or a metal, electrons can line up to become magnetic

MAGNETIC FIELDS Magnetic field lines 1. Leaves north pole & enters south pole 2. Lines closer together = stronger field NOTICE 1. Strongest at the poles 2. Field lines start at the NORTH pole and travel towards the SOUTH pole An area where the force exists; area where force is felt

What is an electromagnet? Electromagnet – a magnet made from a current bearing coil of wire wrapped around an 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 – a machine that changes mechanical energy to electrical energy Generator – a machine that changes mechanical energy to electrical energy Usually use moving magnets to create currents in coils of wire. Usually use moving magnets to create currents in coils of wire.

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

That’s It !!!!