1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 1 Lab 5: DC Circuit Construction (100 points total) You will need to run a simulation to do the lab. Answer the following questions as you work through the lab. Write your answers in blue. (Note that we may miss your response if it does not stand out ) Submit the completed lab in PDF format in Canvas before the due date. Please do not email the lab to us. An email submission will NOT be accepted. Objectives: 1. Calculating current and voltage in different parts of a series/parallel resistor circuits. 2. Measuring current and voltage using an ammeter and voltmeter respectively. Introduction: In Lab #04 you investigated the relationship between voltage, resistance, and current in a simple circuit. In this lab simulation, you will design circuits that are more complicated. You will construct a circuit with resistors in series, in parallel, and a combination of series and parallel. In each of these constructions, you are going to predict the current flowing through a resistor as well as the voltage drop across the resistor using Ohm's Law. You will verify Ohm's Law by measuring current and voltage using Ammeter and Voltmeters. Read Sections 17.3, 18.1, 18.2 and 18.3 for concepts. Lab work (Remember to write your answer in a different font so that it stands out from the instructions) Part 1: Circuit Construction Simulation 1: Open Circuit Construction Kit: DC https://phet.colorado.edu/en/simulations/circuit-construction-kit-dc 1A. Take a few minutes to become familiar with the simulation. Look at the description of different parts of the circuit in next page. Drag different elements to make your circuit. Here are the basics of operations in the simulation: You can use the "Intro" to familiarize yourself with the circuit elements. To add elements to your circuits, simply drag an item into the work area. The default view of the current is the flow of electrons. You can switch to the conventional current to see direction of the current flow. To change the value of an element, click on the item. Change the value of the slider. To uncouple two circuit elements, click on the circular junction and click on the scissor. To measure voltage and current, drag the ammeter and the voltmeter from the left panel. Remember, voltage across an element is measured placing the voltmeter in parallel to the element. Current passing through an element is measured by adding an ammeter in series.

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 2 Write the resistance of the light bulb by clicking on it. ________ Ohm [1 point] Simulation 2. Move out of the "Intro" and select "Lab" (at the bottom) for the rest of Lab 05 Note: You can view the flow of electrons or look at the conventional current. Click on the "Advanced" button. Keep the Wire Resistivity at "tiny" and the Battery Resistance at "0" - the default value. Different parts of the simulation you may find useful Fig 1: A virual circuit showing different parts of the simulation. You may use the following circuit elements for this lab: Battery Light bulbs Low voltage (LV) Low resistance (LRB) High voltage (HV) High resistance (HRB) Resistors Connecting wire Low resistance (LR) High resistance (HR)

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 3 Using Voltmeter and Ammeter An Ammeter is used to measure current flowing through different parts of a circuit. You need to add an ammeter in series with the circuit. The figure in the right shows an ammeter connected between two resistors in series. An ammeter in series is inserted by breaking the circuit as shown in as shown in Fig 2A. This is the usual method of using a traditional ammeter. You can find a different type of ammeter (called clamp-on meter) these days. The ammeters are used by without not breaking the circuit (Fig 2B). The simulation has clamp on ammeters available ( Fig 2C). We will use the regular ammeter in series (as shown in Fig 2A) for our simulations unless stated otherwise. A Voltmeter is used to measure the potential (voltage) drop across a circuit element. You need to connect the voltmeter in parallel to the circuit element. The figures show a voltmeter used to measure the voltage drop across a light bulb and across a resistor. Notice that the probes are in parallel to the light bulb and to the resistor. The red probe of the voltmeter is designed to be at a higher potential. If you read a negative value in the voltmeter, just switch the probes. 2A: Measuring Voltage and Current Drag a resistor (LR), two light bulbs (LRB) and a battery (LV) into the work area. (Here "L" stands for "Low". See above). Change the resistance to R = 4 . You can bring in connecting wires as needed. Construct the circuit shown on the right, consisting of two light bulbs (with the same resistance, 10.0 ) in series with a battery. (The resistor R will be added later). Increase the voltage across the battery to 20 V using the slider. 2A (i) Predict: What will happen to the current drawn from the battery when you place a (R = 4 ) resistor in parallel with bulb #2 as shown in the diagram? Explain your reasoning. [2 points] 2A (ii) Construct: a circuit with the two light bulbs and battery first. Observe the brightness of the light bulbs. Add the resistor R in parallel to Bulb 2. What happens to the brightness of the light bulbs? Does it agree with your prediction above? Write your answer below. [2 points]

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 4 2A (iii) Measure the potential difference across the battery, and then place an ammeter in the circuit so that you can measure the current drawn from the battery. Measure and record the battery voltage and current below. Look at the figure as an example if you are not sure how the circuit should look like. Note if your voltmeter reads a negative value, just switch the red and black probes. [2 points] Current:______________ Voltage: _____________ 2B: Computing the Resistance of a Light Bulb Build a circuit consisting of a battery in series with a 15 resistor and one light bulb (see Figure below). 2B (i). Set the voltage of the battery to 30 V. Using the voltmeter with needle probes, measure the potential difference () across the battery, the voltage drop ( ) across the 15 resistor, and the voltage drop ( ) across the light bulb. What is the relationship between the three measured voltages , , and ? [3 points] : ___________ : ___________ R : _______ Relationship: [2 points] 2B (ii). Using the known resistance of the resistor, calculate the current ( ) flowing though the resistor. Now set up the ammeter to measure the current flowing though the resistor. Does this value match the calculated IR from the previous step? [1+1+2 = 4 points] Calculated = ________ Measured = _________ Comment:

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 5 2B (iii). How is the current flowing though the light bulb ( ) related to the current flowing through the resistor ( )? [2 points] 2B (iv). Calculate the resistance of the bulb, RBULB. Compare this with the measured value found earlier. [2 points] 2B (v). Using the measurements and calculations from this section, how much power is dissipated in the 15 resistor? How much power is dissipated in the light bulb? [2 points] PR _______ PBULB _______ 2B(vi). Multiply the current in the circuit with the battery voltage. This gives the power supplied by the battery. What relationship can you find between this value and the Power values calculated above? [2 points] Simulation 3: Two Bulbs in Series 3A. Construct the circuit shown in the right containing a single light bulb. Set the battery voltage to 20 V. Using the voltmeter and the needle probes, measure the voltage difference across the light bulb. Then use the ammeter to measure the current flowing from the battery. Record your results. [2 points] I ___________ 3B. Predict: what will happen if a second bulb is added in series with the first bulb. [4 points] How will the bulb brightness change? _________ How will the current flowing through the first bulb change? _______

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 6 How will the current drawn from the battery change? ______ How will the voltage across the first bulb change? _____ How will the power change (for each bulb and in total) if at all? Explain your reasoning. [3 points] 3C. Construct: Add a second bulb to the circuit in series with the first bulb (as shown in the Figure). How does the brightness compare to the single-bulb case? [2 points] 3D. Measure the voltage difference across each bulb and record the result. Using the ammeter, measure the current coming from the battery and record the result. [3 points] VBulb1 = ________ VBulb2 = ________ I = _______ Do these results match your predictions? If not, explain the measurement. [2 points] 3E. Measurement of current: Use the clamp-on ammeter and place it in three different places around the circuit. Note that you do not need to break the circuit to use the clamp-on ammeter. Record the current _________ [2 points] Do you see any difference in the values of the current as you move the ammeter around? _________ (yes / no) [2 points] Simulation 4: Two Bulbs in Parallel 4A. Construct: the circuit shown in the right, containing a single light bulb. Set the battery voltage to 10 V. [2 points] Using the voltmeter and the needle probes, measure the voltage difference across the light bulb. ______ Use the ammeter to measure the current flowing out of the battery. Record your results. ________ 4B. Predict: what will happen if a second bulb is added in parallel with the first bulb.

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 7 [5 points] How will the bulb brightness change? ______ How will the current flowing through the first bulb change? _____ How will the current coming out of the battery change? _______ How will the voltage across the first bulb change? _____ How will the power change (for each bulb and in total) if at all? ______ Explain your reasoning with a couple of sentences. [2 points] 4C. Add a second bulb to the circuit in parallel with the first bulb (as shown in the Figure). How does the brightness compare to the single-bulb case? [2 points] ___________ 4D. Measure the current flowing in various parts of the circuit (1,2 ..., 7) using the clamp-on ammeter. Record the values below. [7 points] 1. 1 ____ Amp; 2. 2 ____ Amp; 3. 3 ____ Amp; 4. 4 ____ Amp; 5. 5 ____ Amp; 6. 6 ____ Amp; 7. 7 ____ Amp Relationship between all the currents various parts of the circuit:_____________ [2 points] Explain why the different values make sense. [2 points] Simulation 5: Series and Parallel Combination of Bulbs in a circuit 5A. Do not build the following circuit. First, rank the potential difference across resistors A, B, C, and D in order from highest to lowest BEFORE the break in the circuit is made (circuit a). All four resistors are identical with resistance, R (say) and the battery voltage is V.

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 8 Potential difference rank ____________ [2 points] 5B. Rank the current passing through each resistor. Current rank ____________________ [2 points] 5C. What happens to the current passing through resistor A after the circuit is broken at the arrow shown above? [2 points] Does it increase/ decrease/ remain the same? Explain your answer below: 5D. What happens to the current passing through resistor B, after the circuit is broken? [2 points] Does the current increase/ decrease/ remain the same? Explain your answer below: 5E. Build the circuit now and test your prediction. Set the battery voltage to 30 V. Add a switch where the "break" appears. Were your predictions correct? Set the resistance to R = 10. How does your prediction compare to the experiment? [2 points] Answer:

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 9 6. Conclusion Questions: [2 x 12 = 24 points total] 1. Make a sketch to show how you would connect three identical light bulbs in parallel to the battery, while using the ammeter to measure the current flowing out of the battery and voltmeter to measure the voltage across one of the bulbs. Sketch: 2. Rank the brightness of each bulb (A, B, C, D, and E) from brightest to dimmest. Rank: _________ 3. If the resistance of a bulb is R, what will be the equivalent resistance (in terms of R) of the two bulbs connected in series and in parallel as shown in the figure above? Series: _________ Parallel: __________ 4. Which of the following statements is/are true about the following circuits? Assume all batteries and all bulbs are identical. a) Bulb A does not turn on because the voltage across it is zero. b) Bulb B does not turn on because the voltage across it is zero. c) Bulb C does not turn on because the current flowing through it is zero.

1102L-080/081; Lab 05 Rabbit year, Sum2, 2023 Simulation created by the Physics Education Technology Project (PhET) c/o The University of Colorado at Boulder http://phet.colorado.edu/ 10 d) Answers (a) and (b) are both true. e) Answers (a), (b), and (c) are all true. True: ______ 5. What is the correct order for the total power dissipated in the following circuits, from least to greatest? Assume all bulbs and all batteries are identical. Ignore any internal resistance of the batteries. a) A < B = C < D < E b) D < C < B = E < A c) D < B < E < A < C d) A = B < D < C < E e) B < A < C = D < E 6. To assure the same voltage is available to all devices; my house is wired in series / parallel. 7. In a series circuit, as light bulbs are added, the voltage at the battery increase / decreases / remains the same. 8. In a series circuit, as light bulbs are added, the current at the battery increase / decreases / remains the same. 9. In a parallel circuit, as light bulbs are added, the voltage at the battery increase / decreases / remains the same. 10. In a parallel circuit, as light bulbs are added, the current at the battery increase / decreases / remains the same. 11. A flashlight bulb with potential difference of 5.0V across it has a resistance of 5.0. How much current is in the bulb filament? ____________ 12. How much power does a flashlight dissipate if it runs on two 1.5V batteries and has a bulb with resistance of 15 ? ________________