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DC I Lesson Objectives: 1. What is Electricity? 2. Discover the Electron 3. Learn about Conductors and Insulators 4. Learn about Voltage and Current 5. Learn the difference between DC and AC electricity 6. Wire and Study the Basic electrical Circuit 7. Learn different Electrical Symbols 8. Wire and learn what a Switch does in a circuit 9. Wire and Study the Series Circuit 10. Wire batteries in series and learn what happens 11. Wire and Study the Parallel Circuit
We use the word electricity every day to describe a type of energy source that is so important to the way we live. Electricity lights and heats our homes and businesses, powers many appliances such as televisions and electronics, cooks our food, spins motors and the list keeps going, but exactly what is electricity? We see the effects of electricity every day in the form of heat, light, motion, sparks, sound, and magnetism
Yet, electricity by itself we can t see, because electricity is energy that is invisible. All materials around us are made up of very small building blocks called atoms. Atoms are too small to see and there are millions of atoms in an object. Each atom is like a small solar system with a middle called the nucleus and outer planets spinning around the nucleus called electrons. See the picture below. If an outside pressure is put on some types of materials, electrons move away from the nucleus of the atom and travel to other atoms or even travel to other objects they touch. The ability to move electrons is called ELECTRICITY! Electron ATOMS Nucleus:contains protons
Some material s atoms hold on to their electrons and refuse to let them go or great outside forces are necessary to break them free. Thus, they do not conduct electricity very well. These materials are called insulators. Plastics, glass, dry wood, rubber and even air are examples of insulators. Other materials, such as metals have ample amounts of free electrons moving about from atom to atom. Such materials conduct electricity very easily and are called conductors. Copper is an extremely good conductor and is the popular choice for making electrical wire. Rubber is an excellent insulator and commonly used as the outside jacket of electrical wire. Insulators around conductors keep electrons contained!
Outside pressure is needed to separate electrons from atoms and move them. Friction, magnetism with motion, and chemical reactions do this electron separation. Chemicals inside a battery react separating electrons from their atoms and builds up pressure to one side. This electrical pressure is called voltage. Voltage is measured in volts. A voltage source such as a battery will have two poles, one is the negative pole and the other is the positive pole. Electrons that move away and cluster create the negative pole. Example of Voltage is the Battery! A battery is an electrical energy source.
A conductor at rest. Millions and millions of electrons shooting off in all directions, moving from atom to atom. Current is flow of electrons. Ampere (or Amps) is the measure of current. Electrons move from the negative to the positive. A conductor under pressure by a battery. The pressure of the battery causes electrons to align and move quickly to the positive terminal thus, producing electron flow! + - 1.5V DRY CELL
D.C. stands for Direct Current Direct current electricity flows in one direction all the time. Electricity using batteries is DC electricity. The poles of a battery always stay the same, one side negative and one side positive. A.C. electricity is known as Alternating Current. The electrical source switches (alternates) polarity many times a second. AC electricity is what comes out our home outlets and is HIGH VOLTAGE! Never play with power from outlets because HIGH VOLTAGE can HURT you! + - Hello. I am a 6 Volt lantern battery. Ready to experiment with electricity? Let s go to it!
Electrical Circuit A circuit is much like a circle. A circuit has a path that starts at the beginning and the end comes right back to the beginning. An electrical circuit is a path where electricity can flow from negative pole of a voltage source and come back to the positive pole. The part of the electric circuit that makes electricity do work is called a load. A sample of electrical loads are lamps, motors, heating elements, buzzers. The load pushes back electrons making them work harder to get to the positive side. Pushing back is called resistance.
Here is a simple circuit with a battery, wires, and lamp. What is the source? What is the load? Build this circuit and see what happens! + - Note: Wire colors can help identify the negative and positive terminals. Dark colored wires (black) will always be on the negative side and light color wires (white or red) will be on the positive.
Using Symbols! How it works: Electrons move from the negative side of the battery through the light bulb where work is done as electrons move through the thin wire inside the light bulb (called the filament) producing light. The electrons travel back to the positive side of the battery.
A Basic Electrical Circuit
How it works: In this circuit a switch is placed in between the battery and lamp. The metal blade of the switch is open and electrons do not have a path to travel back to the positive side of the battery. The lamp does not light. The switch breaks the circuit, also called an open circuit.
How it works: In this circuit a switch is placed in between the battery and lamp. The metal blade of the switch is a conductor and since the switch is closed electrons have a path from the battery through the switch, through the light back to the positive side of the battery. This is called an closed circuit.
Close-up of the simple single-pole switch and wiring.
Simple Switch Circuit
How it works: In this circuit a second lamp is added. Look how the second lamp is wired with the red wire. This is called a series circuit as the second lamp follows the first lamp in series. The switch is open so electrons can t flow.
How it works: In this circuit two lamps are wired one right after the other, in series. When the switch is closed electrons flow from the negative pole of the battery through the switch and through one lamp and then through the second lamp before returning to the battery.
Series Circuit
Challenge: What happens if you turn one battery around and connect the positive to the positive of the other battery? Try it and find out! How it works: Electrical loads are not the only electrical devices that can be connected in series. Voltage sources like batteries can also be connected in series. By connecting the battery poles negative to positive the total voltage is 6 volts + 6 volts = 12 volts. The lamps in series add resistance to the circuit. Since each light bulb is the same type, the total voltage is divided by 2 across each lamp, in this case 12 volts / 2 = 6 volts at each lamp.
How it works: In this circuit a second lamp is added. Look how the second lamp is wired with the red and white wire. This is called a parallel circuit as the second lamp is an extension of the first lamp. Look how the red and white wires are in parallel like railroad tracks. The switch is open so electrons can t flow. How will electricity flow when the switch is closed?
How it works: In this circuit two lamps are wired so one lamp is extended from the other. This is called a parallel circuit. Look how the red and white wire is in parallel. Trace the electrons from the negative pole of the battery back to the positive pole. When the switch is closed electrons have two separate paths through the lamps to get back to the battery. Electrical current will be more because two lamps in parallel let more electricity flow, faster!
Parallel Circuit
Hope you had fun! + - Protected Under 18 U.S.C. 707