Parallel circuit lab report

PHYS 1119 Experiment NAME: ________________________________ SECTION: ____ 4 PARTNER: _____________________________ Series and Parallel Circuits Components in an electrical circuit are in series when they are connected one after the other, so that the same current flows through both of them. Components are in parallel when they are in alternate branches of a circuit. Series and parallel circuits function differently. You may have noticed the differences in electrical circuits you use. When using some types of older decorative holiday light circuits, if one lamp is removed, the whole string of lamps goes off. These lamps are in series. When a light bulb is removed in your home, the other lights stay on. Household wiring is normally in parallel. You can monitor these circuits using a Current Probe and a Differential Voltage Probe and see how they operate. One goal of this experiment is to study circuits made up of two or more resistors in series or parallel. You can then use Ohm’s law to determine the equivalent resistance of the resistor systems. Series Resistors Parallel Resistors Figure 1 OBJECTIVES • • • To study current flow in series and parallel circuits. To study potential differences in series and parallel circuits. Use Ohm’s law to calculate equivalent resistance of series and parallel circuits. MATERIALS computer Circuit Construction Kit: DC – PhET Simulation Logger Pro Physics with Vernier © Vernier Software & Technology 4-1 Experiment 4 PRELIMINARY QUESTIONS (Series and Parallel Bulbs recording on D2L shows how to set up this part of the lab.) 1. Wire three bulbs in series. Turn up the voltage until they all light. Turn down the voltage until the bulbs almost go out. What do you observe? Are all the bulbs the same brightness? What happens if you change the resistance of one of the bulbs? What happens if you remove/disconnect one of the bulbs? What happens to the other bulbs? Work with the simulation looking at what happens when you change different parameters and record your results here 2. Repeat Preliminary Question 1 for a parallel circuit. Record your results here. 3. Compare your findings for the bulbs in series to those in parallel. What are the differences? 4-2 Physics with Vernier Series and Parallel Circuits PROCEDURE 1. Use Circuit Construction Kit: DC – PhET Simulation to construct the circuit shown in Figure 2. R1 and R2 to 10 . This is the resistor in the circuit and that appears at the bottom of 2. Set the resistance in done by selecting moving the slide bar the screen. 3. Make sure the probe are in the voltage probe and current proper locations in the figure. Figure 2 You can toggle between symbol and picture notation for the parts by using the selection buttons near the bottom left of the screen. 4. Set the battery (power supply) to 3 V. This can be done by selecting the battery and then moving the slider that appears at the bottom of the screen. Figure 3 Insert a screen shot of your completed circuit. Part I Series Circuits 5. Close the switch and record the readings from the current and voltage meter in the table below. VTOT is the voltage drop across both R1 and R2. 6. Move the leads of the Voltage Probe so they are only across resistor 1. Make sure the switch is closed to complete the circuit and read this voltage (V1). Record this value in the data table below. 7. Move the leads of the Voltage Probe across resistor 2. Make sure the switch is closed to complete the circuit and read this voltage (V2). Record this value in the data table below. 8. Repeat Steps 5–7 with a 51  resistor substituted for resistor 2. 9. Repeat Steps 5–7 with 51  resistors for both resistor 1 and resistor 2. R1 () R2 () 1 10 10 2 10 51 3 51 51 Physics with Vernier I (A) V1 (V) V2 (V) Req () VTOT (V) 4-3 Experiment 4 Part II Parallel circuits 10. Use Circuit Construction Kit: DC – PhET Simulation to construct the circuit shown in in Figure 4 using 51  resistors for both resistor 1 and resistor 2. As in the previous circuit, the Voltage Probe is used to measure the voltage across the resistors, but this time you will measure each resistor separately.