Arizona State University LO2 CIRCUIT LAB 1 INTRODUCTION You will explore properties of electricity in circuits via a PhET virtual lab. 2 MATERIALS For this virtual electricity lab, you will be using the PhET Circuit Construction Kit. 3 SAFETY Review the safety guidelines from the safety contract you & your guardian signed at the start of this course. 4 PROCEDURE INSTRUCTIONS Below are some general guidelines for how to use the Circuit Construction Kit. Choose Lab mode. Drag circuit parts into the blue area to build your circuit. Left-click on the middle of the component to move it. Left-click on the end of a component to stretch a wire or pivot a component. If you add a switch to your circuit, you must click and drag the switch to close it or open it. Left-click on a junction to split the junction and add another component. Left-click on a battery to change its voltage or internal resistance; left-click on a light bulb or resistor to change its resistance. To use the voltmeter, drag the red and black probes to the section of the circuit where you want to measure voltage. You may use an ammeter which becomes part of the circuit or a non-contact ammeter. To use the non-contact ammeter, drag it over the section of the circuit where you want to measure current. Arizona State University Cwewt Diagram Symbols battery 1' |-_m-_' b () resistor ANV ammeter @ voltmeter @ PART A: OBSERVING VOLTAGE RELATIONSHIPS Make circuits with one, two, and three batteries. Use a voltmeter to measure the voltage in each of the circuits and record your data below. Battery Voltage (V) 1. Describe the relationship between the number of batteries and the voltage. Using evidence from the data table, explain what you think might be happening. PART B: USING VOLTAGE Build a circuit with a battery and a light bulb. 2. Draw what your circuit looks like in your notebook. 3. Vary the voltage of the battery and describe how the brightness is affected by voltage. PULEUTES AL LI By 4. Think about a real light bulb and battery in a flashlight; explain what you think is happening that causes changes in brightness. PART C: USING VOLTAGE IN SERIES CIRCUITS Build the circuits below with a battery at about 12 volts and the light bulbs appropriately arranged. Turn on the voltmeter and ammeter to measure voltage of the battery and current into it. Record bulb brightness with descriptive language. Then measure the voltage across each bulb. +| .- +| - +] ,- # of bulbs Battery Voltage (V) Current into Brightness of Voltage across batter bulbs each y (A) bulb | 1 | 2 | 3 5. Summarize the relationships you observed (direct relationship, no relationship, or inverse relationship). 6. Explain what you think is happening in terms of the electrons as more bulbs are added to the circuit. 7. Test to see if changing the battery voltage causes you to modify any of your conclusions. Record what you measured and any conclusions you draw from your tests. 8. In either the 2- or 3-bulb series circuit, remove one of the bulbs without reconnecting the wires. Explain what you think is happening. PART D: OBSERVING VOLTAGE AND CURRENT RELATIONSHIPS WITH RESISTORS Make circuits like the ones shown below, using a resistor that is less than 100Q. Record your data in the table below. Battery Voltage (V) Current (A) 9. Explain what might be happening (in terms of the electrons) to cause the change in current. 10. How are current and battery voltage related? What would be the shape of the graph? PART E: OBSERVING VOLTAGE AND CURRENT RELATIONSHIPS FOR VARIOUS RESISTORS Build a circuit as shown in the diagram below. Click the Values button to display the resistance of all of the resistors. Using the voltmeter, measure the voltage across one resistor or a series of resistors to collect at least 10 sets of data. For example, in the diagram below, the voltmeter is measuring across two resistors totaling 7Q. Arizona State University 12V Ammeter U Resistance (if 2 or more, Voltage (V) Current (A) show sum) Example: 30 + 40 = 70Resistance (if 2 or more, Voltage (V) Current (A) show sum) 11. Describe what you think is happening within the circuit to make sense of the relationships. This experiment is similar to the one where you varied the number of light bulbs. (Remember light bulbs are just glowing resistors)