Procedure: Part 1: Resistors in Series. We will use a PHET applet to create a circuit with three resistors connected in parallel and use it to determine the voltage and current through each of the resistors as well as the total effective resistance of the circuit. 1. Go to: https://phet.colorado.edu/sims/html/circuit-construction-kit-dc-virtual- lab/latest/circuitconstruction-kit-dc-virtual-lab_en.html A screen will load that looks like the following: Tick "Values" in the top box. Show Current Electrons Wire O Conventional Labels O Values Battery Ammeter o ight Bulb + Wire Resistivity Resistor + Battery Resistance Switch Circuit Construction Kit: DC - Virtual Lab PHET. : 2. From the white menu at the left side and the meter box on the right, grab and assemble a battery, a switch, 3 resistors, 4 ammeters and as many wires as you need to create the circuit shown below. If you want to get rid of an item, click on it and then hit the trash can logo that appears at the bottom of the screen To disconnect two items from each other click on the circle betweenShow Durant 10.0 0 O ca values 10.0 0 10.0 0 Tap circuit elen Circuit Construction Kit: DC - Virtual Lab PHET : Click on each resistors to change their values by sliding the bar at the bottom of the screen: set the one on the left (Resistor 1) to 25.0 ohms, the one at the top (Resistor 2) to 50.0 ohms and the one at the right (Resistor 3) to 100 ohms. Notice that their values show up on the screen, and the color of the lines on the resistors changes as well, to reflect the color coding of resistors. 4. Click on the battery to set its value to 10.0 Volts. Note that it is set to have an internal resistance of 0.00 Ohms. 5. Be careful to check that none of your junctions have a red circle, that means that the connection is not made, and current will not flow. 6. At the bottom right, toggle between lifelike and schematic to see how the picture changes. Leave it in the setup which with you feel most comfortable. You are now ready to perform the experiment. To start the current flowing, close the switch by dragging the handle so that it is in line with the circuit. You will then see the little blue dots (which represent negative charges) flowing through the wires. Now measure the voltage across and the current through each of resistors 1, 2 and 3 and record them in Table 1. The current will be read from the ammeter connected directly to each resistor. To read the voltage, pull the voltmeter from its box on the right onto the screen, and drag the red probe on the voltmeter to one side of the resistor and the black probe to the other side. Make sure you get a positive reading: you may have to reverse the order of your red and black probes to do this. You will also need to record the voltage and current across the entire resistor circuit. To do this, drag the red probe of the voltmeter to the bottom left corner and the black probe to the bottom right comer. The "total current" will be read from the ammeter attached to the battery. Change the battery voltage to 20. 30, and 40 volts and repeat.Page Table 1: Experimental Data: Resistors in Series V123 Voltage I123 Battery V1 Voltage |It V2 Voltage Iz V: Voltage Is Current Voltage across RI Current across R2 Current across R3 Current across entire () (V) through through circuit (V) through through RI(A) R2(A) R(A) battery (A) 10.0 20.0 30.0 40.0 What do you notice if you compare all of the currents for a given voltage setting? Is this what you expected? What is the relationship between the voltages? Fill in Table 2 below, using the data from Table 1, and the following relationships: - V1; R2 - 1, : R3 - Ta' -V2 ; R..exp - 7123 V123 , Ry.theoretica = Ri + R2 + Ra From our initial setting, we expect R. - 25 + 50 + 100 - 175$2. If the equations are correct, then the theoretical and experimental values for R. should be the same. Calculate the percent different between them: did the experiment work? How close is the theoretical resistance to 1752? Table 2: Analysis: Resistors in Series Battery R1 ( $2 ) R2 ($2 ) R: ($2) Re,exp ($2) Re,theory ($2)% Voltage difference (V) 10.0 20.0 30.0 40.0 Do your experimental values for Ry. R. and Ra agree with the values you set them to be when you made the circuit? Are they dependent on the battery voltage? Why or why not? Drag the voltmeter so that you have one probe on either side of an ammeter. What is the voltage drop across an ammeter? What does this mean about its resistance?Page Finally, with your circuit still set up, set your battery voltage to 100V by clicking on it. You will record only the voltage and current across the entire resistor circuit. To do this, drag the red probe of the voltmeter to the bottom left comer and the black probe to the bottom right corner. The "total current" will be read from the ammeter attached to the battery. Now click on each resistor to set their values to the values shown in Table 3 below. Record the total voltage and total current. Then calculate Rs....7, _Vizz ; Ry.theoretica = Ri + R2 + Ry for these resistance combinations. Table 3: Total Resistance for different combinations Resistance () V 123 (V I123 (A) Re.exp ($2) Rs, theory ($2) R1-100,R2-50,R3-75 R1-50,R2-50,R3-50 R1-25,R2-50,R3-75 Part 2: Resistors in Parallel 1. Now rearrange the same components from the first part to connect the three resistors in parallel. To disconnect two items from each other, click on the circle between them and hit the scissors icon to disconnect the junction. You may need to grab more wires to make this circuit. If it is easier for you, hit the RESET ALL button and start from scratch. 2. Make sure that your three resistors are arranged EXACTLY as shown in the figure below (look at the color bars), or your results in the table will be incorrect. Ri (25 ohms) should be in the lowest branch, R2 (50 ohms) should be in the middle branch and Rs (100 ohms) should be in the top branch. Change the battery voltage back to 10V. 3. Be careful to check that none of your junctions have a red circle: that means that the connection is not made, and current will not flow. 4. At the bottom right, toggle between lifelike and schematic picture changes. Leave it in the setup which with you feel most comfortable. to see how theShow Current Electrons Conventional 100.0 0 Labels Wire Values Battery SV Wire Resistivity 50.0 0 DOO Light Bulb 19 090A Resistor Ballcry Resistance 25.0 0 Skitch 200 0 10.0 V O Tap circuit element to edit. You are now ready to complete the experiment. To start the current flowing, close the switch like you did in part 1. You will then see the little blue dots (which represent charges) flowing through the wires. Now record the voltage across and the current through each of resistors 1, 2 and 3 in Table 4. The current will be read from the ammeter connected directly to each resistor. To read the voltage, drag the red probe on the voltmeter to one side of the resistor and the black probe to the other side. Make sure you get a positive reading. You will also need to record the voltage and current across the whole circuit. To do this, drag the red probe of the voltmeter to the bottom left comer and the black probe to the bottom right comer of the circuit. The "total current" will be read from the ammeter attached to the battery. Change the battery voltage to 20, 30 and 40 volts and repeat. Table 4: Experimental Data: Resistors in Parallel Battery Vi Voltage V2 Voltage | 12 V3 Voltage | 13 V123 Voltage Voltage I123 across RI Current across R2 Current across R3 Current (V) (V) through across entire through Current (V) through RI (A) R2(A circuit (V) R;(A) through battery (A) 10.0 20.0 30.0 40.0What do you notice about all of the currents? Is this what you expected? What is the relationship between the voltages? Is this what you expected? Fill in Table 5 below, using the data from Table 4, and the following relationships: - 2 . R3 -:RD.exp - V123 , Rp.theoretical ( R , + R 2 + Rs) From equation 6, we expect Ry.moorenear - ( + so Too) - (0.07) 1 - 14.30. If the equations are correct, then the theoretical and experimental values for Ro should be the same. Calculate the percent different between them: did the experiment work? How close is the theoretical value for Ro to 14.352 Table 5: Analysis: Resistors in Parallel Battery RI ($2) R2 ($2) R3 (52 ) Rp.exp($2) Rp, theory % Voltage (52) difference (V) 10.0 20.0 30.0 40.0 Do your experimental values for Ri,R. and Rs agree with the values you set them to be when you made the circuit? Are they dependent on the battery voltage? Why or why not? Finally, with your circuit still set up, you will record only the voltage and current across the entire circuit. To do this, drag the red probe of the voltmeter to the bottom left corner and the black probe to the bottom right comer. The "total current" will be read from the ammeter attached to the battery. Now click on each resistor to set their values to the values shown in Table 6 below. Record the total voltage and total current. Then calculate Rp.exp ~ 7.2, V43 ; Rep.theoretical = (R. + +) * R,) for these resistance combinations. Table 6: Total Resistance for different combinations Resistance V123 (V) I123(A) RP, exp ($2) R1=100,R2-50,RJ-75 Rp. theory ($2) R1-50,R2=50.R3-50 R1=25,R2=50,R3-75