Electricity and Magnetism This is what we have discovered so far. There is no theme for this because these should be in your notes already. If you don’t have it in your notes then you better hurry to write it down.

Magnetism All magnets have two poles. North and South. You cannot separate a magnet into just one pole. Magnets exert a force (attract and repel). Non-metallic items are not attracted nor repelled Not all metals are attracted nor repelled. Magnets can work through objects. Magnets can attract or repel through non-magnetic materials, ie your desk, hand, plastic, etc. Magnets vary in size shape and color but that does not matter to determine the strength of the magnet. A small magnet can have a higher strength than a larger magnet Magnets have a field that surrounds them. The field goes from North to South poles. This is the area that exerts the force. The larger the separation in lines the less magnetic force. The further away from a magnet the less the force.

Electricity The information in black font is what should be written in your notebooks from the presentations. The red font indicates new information. All of the presentations had to do with one type of electricity. Current electricity Current electricity is the continuous flow of electric charge. There are two types of current electricity.

Current Electricity You investigated the flow of electricity through a system. The system contained wires, resistors, and a power source. In order for energy to flow the system has to be complete.

Two Ways for Energy to Flow Alternating current: Abbreviated AC This type of current can alternate directions. This is what type of current is in our homes, schools, businesses, etc. In your experiments you may have noticed that when you connected the positive side of one battery to the positive side of another the light wouldn’t light. Direct current: This current can only flow in one direction. Flashlights, cell phones, computers, etc. all run on direct current. That’s why you have the big plug to convert AC to DC.

Parts needed for Energy to flow Power source Wires That is all you need for energy to flow. That is the simplest circuit. Energy flows from the negative to the positive. But how can you tell energy is flowing?

Energy Flow Slowed Many of you discovered that the light bulbs will light up, fans will spin, bell will ring, and sound can be made when connected to the power source. With relation to the light bulbs you noticed that the bulbs did not light up the same. They were all different brightness. Even if you added more power they became brighter but not all the same brightness.

Resistors Each item in the circuit other than the power source will resist the flow of energy. Resistors – oppose the flow of energy. The wire and the items in the circuit are all slowing down the flow of energy. So by the time the energy reached the last bulb it was reduced so much that there wasn’t enough to produce the same light.

Wires as a Resistor An experiment proved that the longer the wire the more the resistance to flow, the shorter the wire the less resistance to flow. This was evidenced by the light bulb being brighter for a shorter wire compared to dimmer for longer wires. Not only is length a factor to increase resistance but so is thickness. The thinner the wire the more resistance to flow. The thicker the wire the less resistance to flow. Finally, the temperature of the wire can aid in resistance. The cooler the wire the less resistance to flow. The warmer the wire the more resistant to flow. Items in the system can slow down flow as well; the fan, lights, bells, anything connected to the wire aids in slowing down the flow. All are considered resistors.

In Summary We have proven that current electricity is the flow of energy from a power source through a system and that flow must return back to the power source. We have also shown that items in the system can reduce the flow of the energy.

Conductors and Insulators Another thing that you proved in your experiments is that there are items that help the flow of electricity. Conductors – material that charge can easily flow through. Metals make very good conductors. Metals are made of ions with free electrons. We know electrons are a charged particle. The electrons move freely along the metal. That means electricity is the movement of electrons.

Conductors and Insulators You also showed that there are some materials that electrons (electric charge) cannot flow through. Insulators – materials that charge (electrons) cannot easily flow through. These materials do not have free electrons so the energy cannot flow. Most materials are insulators.

Types of Circuits Many of you showed that we need to connect one end of a battery to another in order to create a circuit. Circuit – Complete path for energy to flow from a power source and return to the power source. Many discovered that your light wouldn’t light unless you connected back to the same battery. Or if there was an opening in the circuit. Or if the light bulb was broken. All of the above represent a “break” in the circuit. Any break in the system stops the flow of electrons.

Beneficial Breaks Can you think of a time when I would intentionally want to break the system? Switches – intentionally break the system to stop the flow of electrons. But how do I install a switch to turn something off without turning off all items in the system? Kinda like the demonstration lights. Or the lights in the class. Why don’t all devices turn off when I flip the switch?

Two Types of Circuits You may have noticed in some of the experiments that it all depends on how you wire the circuit. The only way items will work in the circuit is if there is a path for the flow of electrons. The electrons pass through the system, through the object and power the object. Right? Break the system anywhere along that flow and the electrons cannot return to the source. So, no power to the objects. There are two ways to get power to objects.

Series Circuits Charge (electrons) have only one path to flow. All items are connected one after the other. If one object in a series circuit stops working then they all stop. Each object also increases the resistance so by the time electrons reach the last object the flow is decreased. If a break occurs anywhere along the circuit the flow stops and all objects stop working.

Series Circuit Diagram Resistors – Light bulbs, fans, TVs, radios, Refrigerators, stoves, etc. Wires Power Source There are two batteries shown here Electron Flow The red arrows show the path the electrons take through the circuit. Notice how there is only one way for the electrons to flow.

Parallel Circuits Charge (electrons) have more than one path to flow. Items in the circuit can be connected one after another or on a separate path. If one object in a parallel circuit stops it may not affect how another object works. The objects still have resistance but the same energy is allowed to flow to the objects. If a break occurs anywhere along the circuit the flow stops only for that section. Depending on where the break is.

Parallel Circuit Diagram You will see many of the same parts to a parallel circuit as you will a series circuit. There is a power source (two again in this diagram), there are wires, and three resistors. The difference is the way the electrons can flow. Look at the path the electrons can flow through the system. Electrons can also travel along this path to the source The electrons can move from the source back to the source along this path. All paths deliver the same amount of energy. Powering all objects the same. They can also move from the source back to the source using this path