Chapter 11 Lesson 01, "How Electricity Flows Through a Circuit"

Materials:

• Worksheet, 11-01 "How Electricity Flows"

Objective:

• Students will explain static electricity.
• Students will explain how electricity moves through a circuit
• Students will compare an open circuit to a closed circuit

Anticipatory Set:* Show the students a picture of a girl with her hair sticking out. Ask the students what is going on in the picture. Show the students a picture of two boys and a balloon stuck to the wall. Ask them what is going on in that picture. Show the students a diagram of what is going on in the first situation and explain it. Show the students a picture of a diagram explaining what is going on in the second picture and explain it.

Teacher Input:* Without thinking about it most people think of wires as the only way to move electricity from one place to another and that is just not the case. You have all rubbed your feet on the floor When you do the floor gives electrons to your feet. This makes your entire body have a negative charge. Then if you move next to another person or a doorknob with your finger you can give up those electrons from your body. They definitely notice when electrons jump into their body. Way back in chapter 3 we learned that atoms have positively charged particles in its nucleus and negatively charged particles flying around the outside. This is where all electrical potential comes from. As in the case of shocking your buddy's ear some atoms gain electrons and others lose electrons. Electricity is the flow of electrons from one atom to another to balance electrons back out again. Since electrons have a mass and are moving very fast electricity has the ability to do work and energy is transferred from one object to the next. Like rubbing a balloon on your head. Hanging balloon is accelerating against gravity. In a thunderstorm air molecules are sliding past one another very quickly. This causes a build up of electrons in one part of the cloud. When those elections are released either to the ground or other parts of the cloud you get lightning.

You have all seen a flashlight before. Show a flashlight and how it is put together. I flashlight has the ability to turn electricity to produce heat and light. Here is how. In a battery you have one part of the battery with a build up of electrons and the other part with a shortage of electrons. The elections want to move from one end of the battery to the other. A flash light is designed to provide electrons a path to go from the positive side to the negative side of the battery. The light bulb is part of that path. The wires leading to the light bulb are large allowing a lot of electrons to move but in the light bulb you have a fine filament. The filament is very small and because so many elections are being forced through it, it glows and heats up. Then the electrons get to large wires again and they go to the positive side of the battery. This is called a closed circuit because it allows electrons to flow from one palace to another, this movement is called electric current. The amount of electric current that is flowing through a wire can be measured with a unit called the Ampere. The path for the electric current is called a circuit. The flashlight also has a switch. Does anyone have a guess about what the switch does to the electric flow.

When the switch is moved so that current can no longer flow it is no longer a closed circuit. It is now called an open circuit. Switches are really quite simple. It is like a door. When it is closed it allows electrons to flow from one side to the other. When it is open electrons can not flow from one side to the other.

When you have an electrical circuits you may want to show someone else the way that the electricity moves. You can do this using a diagram. A diagram that uses symbols to show the parts of the circuit is known as a schematic diagram. Scientists often use drawing of circuits to make a complicated system of wires and switches running all over much more simple. Here are some examples:

Guided Practice:* Students will complete the questions at the end of the section on Page 314. They may work as a group, pairs or with the entire class.

Independent Practice:* Students will complete the worksheet, 11-01 "How Electricity Flows"

Check for Understanding:* Students will complete the quiz, 11-01 "How Electricity Flows through a circuit"

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-1 Students will understand models describing the nature of molecules, atoms, and sub-atomic particles and the relation of the models to the structure and behavior of matter (Structure of Matter);
• SCI A-2 Students will understand the physical, chemical, and nuclear changes and interactions that result in observable changes in the properties of matter (Changes and Interactions of Matter);
• SCI A-5 Students will understand the strength and effects of forces of nature, including gravity and electromagnetic radiation (Forces of Nature);
• SCI A-8 Students will understand the scientific principles and models that
  describe the nature of physical, chemical, and nuclear reactions;
  state that whenever energy is reduced in one place, it is increased somewhere else by the same amount; and
  state that whenever there is a transformation of energy, some energy is spent in ways that make it unavailable for use (Energy Transformations);
• SCI A-9 Students will understand the transfers and transformations of matter and energy that link living things and their physical
• SCI A-15 Students will use science to understand and describe the local environment (Local Knowledge); and: