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

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

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.

The world is filled with electrical charges: + - + + + - - + - + + + - - - + + - - -

What is this electrical potential called? Static Electricity - - - - - + + + - - + +

Static Electricity The 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.

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

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

Static Electricity Balloons Rub balloon against your hair. Record one observation when you hold your balloon near your head Now use another group’s balloon and see how the two balloons react to each other Record your observations using the terms you learned today

Static Electricity Tape Take a 5-6 inch piece of clear tape and fold over the last ½ inch . Press the tape to the table and rub to secure the tape Remove the tape from the table. Bring your tape close to the balloon Record your observations

Static Electricity Tape Take another 5-6 inch piece of clear tape and fold the last ½ inch over just like the first tape Press both pieces of tape against your desk and rub to secure them Remove the tape from the table Move the tape close to each other Record your observations (does the side of the tape matter)

Static Electricity Lightning

Static Electircity Van de Graaf Generator

Static Electricity Van de Graaf Generator

How can we control currents? With circuits. 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.

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

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

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

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

Examples Conductors: Insulators: Metal Water Styrofoam Rubber Plastic Paper

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.

What Influences Resistance? Material of wire – aluminum and copper have low resistance Thickness – the thicker the wire the lower the resistance Length – shorter wire 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 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… Amps measure how much water comes out of a hose. Volts measure how hard the water comes out of a hose.

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

Practice with Ohm’s Law Volts Amps 4 100 25 15 150 10 2 30 9 45 5 6 48 8

What is an electromagnet? 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 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.

That’s It !!!!