Applied Science - Physics (4A) Lab
 OBJECTIVES: Exploring how electricity works. Designing an electrical circuit. VOCABULARY: circuit conductor current MATERIALS: non conductors and conductors circuit set up battery holder batteries Electricity Slideshow Students explore insulators and conductors of electricity.
 BACKGROUND: Electricity is the movement of electrons which creates a current. A circuit is a closed or undisturbed path of electrons through a wire made up of material that conducts electricity. A bulb in a circuit will only light if it is in a closed circuit. Electricity will not go through all materials. If electricity goes through and completes a circuit, it is called a conductor. If electricity doesn't go through to complete the circuit, it is called a non-conductor (or insulator). Insulating materials have electrons so closely bound to the nucleus of the atom that a steady electric current is greatly reduced. In a conductor, usually metals, the "free" electrons can move from atom to atom to permit passage of an electrical current. If there is a restricted flow of electrons through special conditions, it is called a semiconductor. In this lab, students can only detect a conductor or nonconductor. Students will try and determine how to complete a circuit. They have learned about parallel and series circuits in the third grade. If they have forgotten, review those labs. Parallel and series circuits have to do with the direction of the flow. In series circuits, the flow goes from one light to another light. The lights get progressively dimmer because there is not enough voltage to light them all brightly. Only a parallel circuit can maintain the voltage to each bulb at the same intensity. PROCEDURE: Explain to students that they are going to be working with electricity in the form of a current. The energy that creates the current is contained in the battery. This energy is stored in the form of chemical energy.    Explain how electricity has made our lives easier. By operating machines, electricity has freed humans from otherwise tedious tasks. Also discuss how our lives would be affected if electricity could no longer be produced. Have students create a list of things that will and will not work without electricity. Students will be surprised at the amount of machines that use electricity.    This lab looks at the circuit by investigating the battery. A battery is the energy source that creates free electrons. There are several types of batteries on the market, but no matter which battery you use, the information needed will be on each battery. The size of the battery is also labeled. Each battery, no matter how large, is one cell or a series of cells. One cell gives 1.5 volts of electricity. A six-volt battery will have a series of 4 cells of 1.5 volts. If available, show examples of other types of batteries.    For this lab, give each group a battery holder, 2 batteries, a miniature light bulb and different conductors and non-conductors that are provided in the module. You may want to add different materials you have available.    ANSWERS:    Exercise I 1. D 2. 1/2 volts (some may be 1.5 volt) 3. Chemicals that produce free electrons 4. Note: the side with the "bump" is always positive 5. If the light bulb brightens, then the battery is charged. 6. Same thing happens. You can reverse wires and the same reaction occurs. 7. A circuit 8. Because the flow of electrons goes like the arrows in the diagram. 9. The bulb should be a little brighter. 10. Add them up 1.2 + 1.2 = 2.4 volts    Exercise II You can determine if a substance conducts electricity by testing it with a set up like a circuit. If the bulb lights up, it is conducting electricity.
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