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Version Green Investigating Electrical Circuits with The PhET Animation: Circuit Construction Kit-DC only General instructions: You will use one or two online animations, your textbook, section assessments, and your guided notes to help you complete the following investigations. Circuit Construction Kit-DC only This animation allows you to drag objects onto the working area and move them around. Place objects close to each other to connect them. Control-click on a connection to see the options for that connection, including disconnecting the objects. Clicking on an object and using the delete key on your keyboard removes an item. On the right side of the application, you will see some options. Click “show values” in the options area. Use this animation for items 1-9. Key to this Document Instructions are in black. Experimental questions that you need to solve through experimentation with an online animation are in green highlighted. Data tables that you will fill out while experimenting are in aqua highlighting. Items that need a response from you are in yellow highlighted. Please put your answers to this activity in RED. Circuit Basics 1. Using the simulation “Circuit Construction Kit-DC only”, build a circuit that lights a light bulb, but only contains 3 pieces. (Also: Look in chapter 2.4 for help.) Insert a picture of that circuit below. (Use Command-Shift-4 to take a picture of the circuit, and then drag it from your desktop to this document.) What 3 components does every electrical circuit need to be complete? 1A. 1B. 1C. 2. It is called a short circuit when you connect the electrodes of a cell (battery) with just a conductor and no load on the circuit. Make a circuit like the picture below in the simulation. (Use chapter 2.6 for information on short circuits) Version Green 2A. What happens? 2B. How fast are the electrons moving? 2C. What happens to your hands when they rub together very quickly? (This is the same thing that is happening when the electrons rub against the atoms of the wire.) 2D. Why would we want to avoid this? 3. Please make a complete circuit that includes a switch and lights one light bulb when the switch is closed. Insert a picture of that circuit below. (use CommandShift-4 to take a picture of the circuit, and then drag it from your desktop to this document.) Conductors vs. Insulators Keep the circuit you just created in #4, and separate the wires so you can place an object in the gap. Click on the grab bag and select each of the items so they are all on your workspace. 4. Put each of the items into the gap to discover whether it is a conductor or an insulator. List conductor or insulator for each item in the chart below. Item Dollar bill Paper clip Penny Eraser Pencil Lead Hand Dog Conductor or Insulator? Version Green 5. What are all the conductors made of? 6. Why is the pencil lead a bit different than the others? Look VERY closely at the electrons; watch one electron for a little while to see what it does. Current In this section, you will build the circuits under each question and use your observations of the circuits to come to a conclusion/answer for each question. The circuits you build do not need to look the same as the diagrams in shape; they do need to be the same elements as shown by the symbols. 7. How is the amount of current affected by the voltage in a circuit? You will need to change the amount of voltage in the battery, and then for each voltage use the non-contact ammeter to measure the current. Notice also how the brightness of the bulb changes with the amount of current. Data Table Voltage (V) Current( ) <--Fill in the unit! 9V 18V 27V 36V 45V Conclusion: As the amount of voltage increases, the current ____________. 8. How is the amount of current affected by the amount of resistance in a circuit? Version Green You will need to change the amount of resistance provided by the bulb, and then for each resistance use the non-contact ammeter to measure the current. Notice also how the brightness of the bulb changes with the amount of current. Data Table Resistance (ohms) Current( ) <--Fill in the unit! 10 ohms 20 ohms 30 ohms 40 ohms 50 ohms Conclusion: (Look at the last conclusion for how to write your sentence!) Series vs. Parallel Circuits 9. How does the current of a parallel circuit compare to the current in a series circuit with the same amount of bulbs ? Measure the current of each circuit with the non-contact ammeter found on the left. Please set the voltage of your battery to 25 Volts by control-clicking on the battery and choosing “change voltage”. Data Table Number of bulbs Current in series circuit Current in parallel circuit 2 3 4 Use the experiments you just did to answer the following questions: 9A. How does the number of bulbs in series affect the current in a circuit? Version Green 9B. How does the number of bulbs in parallel affect the current in a circuit? 9C. If you have more bulbs in series is there more, less, or no change in the resistance? (Hint: if the brightness goes down, current went down because the resistance is more.) 9D. If you have more bulbs in parallel is there more, less, or no change in the resistance? (Hint: if the brightness goes down, current went down because the resistance is more.) 9E. What happens in a series circuit when you remove 1 bulb? 9F. What happens in a parallel circuit when you remove 1 bulb? Resistance 10. Now you will be using air through a straw to simulate electrons through a wire. Blow through the drinking straw. Next, cut the drinking straw in half and blow through a half-straw. 11. Was it more resistance or less resistance to blow through the shorter straw? 12. Cut the halves again in half, now you should have 4 quarters of a straw. With the four pieces, blow through one, then blow through all four made into a larger, square-shaped straw. 13. Was it more resistance or less resistance to blow through the thicker straw? 15. Use chapter 2.2 to help you with these items. The first one is done as an example for you. Factors that affect resistance What type of wire would have the most resistance 1. Material a material that holds on to electrons tightly like plastic 2. 3. Version Green 4. ______________________________________________________________ Review Statements: use these to see if you have learned the main points of this activity. Underline the correct choice: 1. For a circuit to be complete there must be a(n) broken / unbroken path for electron to flow through. 2. Conductors allow / prevent charges from flowing. 3. Short circuits are dangerous because a. they can cause lots of heat due to electrical friction b. they can catch on fire, or give people electrical shocks c. they can cause an energy source like a battery to be depleted (or “run out of electrical energy”) very quickly d. all of the above. Fill in the blank: 3. As the voltage in a circuit increases, the ____________________ also increases. 4. As the resistance in a circuit increases, the current in the circuit __________________. 5. Wires that are thicker have ___________ resistance than thinner wires. 6. Longer wires have _____________ resistance than shorter wires. 7. When a wire has a ___________ temperature, its resistance becomes less. 8. Series circuits have __________ resistance than parallel circuits. 9. Series circuits have _________ path(s) for electrons to flow on, while parallel circuits have ____________ path(s) for electron flow.