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Table of Contents Career Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Basic Lesson Plans Activity 1 – ElectroLight Battery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Activity 2 – Lights and Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Activity 3 – Ohm’s Law. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Challenge 1 – Holiday Light Manufacturing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Activity 4 – Electronic Schematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Activity 5 – Breadboarding Blinky. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Activity 6 – PCB Blinky. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Activity 7 – Breadboarding the Show. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Challenge 2 – PCB Laser Light Show. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Standards Addressed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Puzzle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Links of Interest. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3 Activity 2 Lights and Switches Teacher Procedure Objective Procedure 1 2 In this activity, students investigate series and parallel circuits while collecting data. Instruct students to get into teams of two. Background Have students follow the Student Procedure to build a series circuit from three lightbulbs, a switch, and a power supply; to use a multimeter to measure the voltage; to build a parallel circuit; and to complete the “Lights and Switches Data Sheet.” The terms series circuit and parallel circuit refer to the way that a circuit is connected. A series circuit is a series of components hooked together along a single path. The current that flows through the first component will be the same current that flows through each component. Traditionally, this was how holiday lights were strung. That’s why the entire strand went off when one lightbulb quit working. That one bad lightbulb created an open circuit so the current could no longer flow. The hard part about a string of lights not working is that it’s difficult to tell which bulb is bad. Eventually, the manufacturers got smart and began producing holiday lights in a parallel circuit configuration. Parallel circuits are wired in such a way that if one bulb goes out the other bulbs will still shine. 11 Activity 2 Lights and Switches Student Procedure 3 4 5 Vocabulary • • • • • • • Next, cut three pieces of wire each three inches long. Strip the ends. closed circuit current open circuit parallel circuit series circuit switch voltage Locate the battery holder, batteries, and knife switch. Loosen the screws on each socket holder and the knife switch. Do not allow the small nut to fall off the socket screw. Materials • • • • • • • • • • • • 3 lamp sockets (Pitsco product 59391) 3 – 1.5V bulbs (Pitsco product 59392) Knife switch (Pitsco product 59395) Electrical wire (Pitsco product 56142) Scissors Wire stripper Ruler Small Phillips and flat-head screwdrivers Multimeter 4 AA battery holder (Pitsco product 32971) 4 AA batteries “Lights and Switches Data Sheet” 6 A series circuit is similar to making a complete circle. Using the wire you cut, string the lights, switch, and battery holder (power source) together to make a complete circle (circuit). Hook the red wire of the battery holder to the right side of the switch. Hook the left side of the switch to the right side of the first bulb. Hook the left side of the first bulb to the right side of the second bulb, and so on. Your last connection should be connecting the black wire of the battery holder to the left side of the third bulb. Procedure 1 2 Get into teams as instructed by your teacher. Build a series circuit using three lightbulbs, a power source, and a switch. First, locate the three lamp sockets and 1.5V bulbs. Screw the bulbs into the lamp sockets. 12 Activity 2 Lights and Switches Student Procedure 7 a complete circuit. Hook the red wire of the battery holder to the right side of the switch. Hook the left side of the switch to the right side of the first bulb. Hook another wire into the right side of the first bulb and connect it to the right side of the second bulb. Then, another wire should connect the right side of the second bulb to the right side of the third bulb. The left side of the third bulb should connect to the right side of the second bulb and then connect to the right side of the first bulb. Open the knife switch (creating an open circuit) and load the batteries into the battery holder. Close the switch and watch the lights illuminate. 8 9 With the series circuit lights on, locate the multimeter. Set it to 20V. In the series circuit, the current is only flowing in one direction (DC, or direct current). You can tell the direction of current flow by placing the red lead on one side of a lightbulb and the black lead on the other side of the same bulb. If the multimeter reads a negative number, the current is flowing in the other direction. 10 Following the instructions on the “Lights and Switches Data Sheet,” fill out the series circuit measurements table. Disassemble the series circuit. 13 The last connection should be connecting the black wire of the battery holder to the left side of the third bulb. Close the switch and watch the lights illuminate. 11 Now construct a parallel circuit using three lightbulbs, a power source, and a switch. Cut two more three-inch pieces of wire. Strip the ends. 14 15 With the parallel circuit lights on, locate the multimeter. Set it to 20V. 12 Following the instructions on the data sheet, fill out the parallel circuit measurements table. Complete the rest of the data sheet. A parallel circuit is similar to having different choices in a traffic jam. If there is an accident on A Street, you can use B or C streets to get to the destination. Using the wire pieces, string the lights, switch, and battery holder (power source) together to make 13 Activity 2 Lights and Switches Student Procedure Lights and Switches Data Sheet Series Circuit Measurements Measure the voltage of the battery pack, across each lightbulb, and across the switch in both the open and closed positions. Voltage off Voltage on Battery pack Lightbulb 1 Lightbulb 2 Lightbulb 3 Add the voltages that are across the three lights when they are turned on. In a series circuit, voltages added across the three lightbulbs should equal the same voltage the battery pack held. Was this true in your circuit? If not, what do you think caused the difference? What caused the changes in voltage across the switch? Unscrew Lightbulb 1. What happens to the other lights? What is the voltage across Lightbulb 1? Lightbulb 2? Lightbulb 3? Screw Lightbulb 1 back in place. What do you think would happen if you unscrew Lightbulb 2 or 3? Try it and see what happens. What can you conclude about a lightbulb burning out in a series circuit? 14 Activity 2 Lights and Switches Student Procedure Lights and Switches Data Sheet continued Parallel Circuit Measurements Measure the voltage of the battery pack, across each lightbulb, and across the switch in both the open and closed positions. Voltage off Voltage on Battery pack Lightbulb 1 Lightbulb 2 Lightbulb 3 Unscrew Lightbulb 1. What happens to the other lights? What is the voltage across Lightbulb 1? Lightbulb 2? Lightbulb 3? Screw Lightbulb 1 back in place. What do you think would happen if you unscrew Lightbulb 2 or 3? Try it and see what happens. What can you conclude about a lightbulb burning out in a parallel circuit? According to your measurements, what is the biggest difference between a series circuit and a parallel circuit? If you have a string of holiday lights (series circuit) on your house, what happens if a lightbulb burns out? Why? If you have a string of holiday lights (parallel circuit) on your house, what happens if a lightbulb burns out? Why? Is it an advantage or disadvantage to purchase lights strung in series? Is it an advantage or disadvantage to purchase lights strung in parallel? 15 Glossary battery – an energy storage device breadboard – a solderless way to connect components or build a prototype soldering – a process that joins two pieces of metal capacitor – a device used to temporarily store electric charge switch – an electronic component that can break or interrupt a circuit (turn a circuit off and on) closed circuit – a continuous circuit trace – the electrical connections on a PCB cold solder joint – a bad solder joint transistor – a device similar to a switch that is open and has no moving parts conductor – a wire or component that conducts electricity current – the electricity that flows through a circuit electrodes – the copper and zinc elements in a battery voltage – a unit of measure for power in a circuit voltage regulator – an electrical component that regulates or maintains the voltage at a constant level electrolyte – the acid solution in a battery LED – light emitting diode; an indicator light in a circuit ohm – a unit of measure for resistance Ohm’s law – Ohm’s law states the current through a conductor is directly proportional to the potential difference or voltage across it and inversely proportional to the resistance. open circuit – a circuit that is not continuous and through which no current is flowing parallel circuit – a side-by-side way of connecting components so that the ends of each component are connected together PCB – a printed circuit board potentiometer – a variable or adjustable resistor resistor – a device that resists the flow of electricity schematic – a diagram that shows a circuit using symbols to represent components series circuit – a way of connecting components one after another so that the same current flows through each one 69