STEP 1 With the power to your bread boa rd off, build the circuit shown in the schematic below. Notice that you should be using red LE D5 in this lab. // D1 02 P33 Red Red 5 v R1 220 Q // Turn the power on and note the brightness of the LEDs. The brightness of an LED correlates with the current through it. If you have 2 of the same type of LED, and one is brighter than the other, the brighter one must have greater current through it than the dimmer one. If they appear to be of the same brightness, the LEDs must have the same (or nearly the same) current through them. Observe carefully; if you look at LEDs from different angles, the brightness will look different, even if it didn't actually change. In other words, the apparent brightness of the LEDs changes according to your viewing angle. If you look at an LED from the top, it will look much brighter than it will look from the side. In order to make comparable observations, choose a viewing angle that you can use consistently for the entire assignment. . What does the relative brightness of the two red LEDs in your circuit tell you about the current through them? (Hint: There should not be any observable difference between the two LEDs.) - Use your voltmeter to measure the voltage across each one of the LEDs with the red probe on the positive lead and the black probe on the negative lead. You should measure approximately the same potential difference across D1 as across D2. This potential difference is what causes current to ow through each LED. 0 Measure the voltage across R1. Since current is owing through R1, there will be a potential difference across the resistor. This schematic can be color coded to show levels of electric potential in the circuit, illustrating the potential differences across the components. Although LEDs are not resistors, there will be a measurable voltage across each of these LEDs, which will affect the color coding you should use. Take a moment to copy the schematic and apply color coding to your schematic drawing before moving on to the next step. STEP 2 Next, you will add a shorting wire across one of the LEDs. In this case, the shorting wire is a jumper wire used to connect both leads of an LED to each other. This is illustrated in the schematic below. The wire effectively acts like a shortcut path for charge to follow. This is true even when the shortcut is a physically longer path. The shorting wire has almost no resistance, so the whole wire will have the same electric potential. That means there will be no potential difference across the wire, or across the shorted LED. Since there is no voltage across the LED, no I I1 across the wire, or across the shorted LED. Since there is no voltage across the LED, no current ows through it. Instead, the current flows through the short, past the LED. Apply color coding to this version of the schematic, using the instructions in Color Coding to Understand Potential Differences as a guide. . What predictions can you make about the circuit based on your color coding? (Consider the path that current will follow and the potential difference across each component.) . What changes should you expect to see in the circuit when the shorting wire is added? (Based on the changes to voltage and current that you just predicted.) // PSB 5 V 220 Q Try "shorting out" the second LED in the series (D2) by connecting a wire to the same breadboard conductors as the leads of D2. . What changes did you observe when you added the shorting wire? (Hint: the shorted LED should go out, while the other LED gets brighter.) o How did those changes compare to your prediction from color coding the schematic? 0 Measure the voltage across the shorted LED. Since the jumper wire is connecting both sides of the LED to each other, there will be no difference in electric potential, so the meter should show zero volts across the LED. Current flows past the LED (through thejumper wire) instead of through it. . Measure the voltage across R1. With D2 shorted, there will be more voltage across the resistor than before. Since the voltage across the resistor has increased, more current will flow through it. That means more current ows through D1, as well. 0 What do you observe when the shorting wire is removed? (Hint: things should go back to the way they were before, with both LEDs lit.) STEP 3 Consider your observations so far. 0 When D2 is shorted: o What does the change in brightness of D1 tell you about the amount of current owing through the LED? (Hint: this is telling you the same thing as the increased voltage across R1.) 0 What is D2 doing in the circuit when it is shorted out? To verify your answer to the last question, connect the shorting wire to the breadboard in the same rows as D2, so that the wire will stay in place on its own. Then, remove D2 from the breadboard while the circuit is on and the shorting wire remains connected. D1, which remains in series with the resistor and the shorting wire, should not show any change in brightness when D2 is removed. STEP 4 Now return D2 to the circuit and try again with a longer shorting wire, or even with two wires that are connected somewhere else on the breadboard to make a long "short". . Are the results different when using a long jumper wire than when using a short one? (Hint: if they are, check that everything is connected as described and try again.) STEP 5 Finally, remove any shorting wires from the breadboard, leaving the original circuit from Step 1. Both LEDs should be lit again, with approximately equal brightness. Predict what you believe should happen if you short D1 instead of D2, and w_hy. Write down both parts of your prediction. Remember that a valid prediction must include the reason for the expected outcome. Take the wire that you rst used to short D2 and use it to short D1 and observe the results. . Do the observed results match your prediction? . If not, what differences do you observe and how might they be explained? Question 1 1 pts When two red LEDs are connected in series with a resistor, as shown in the schematic below, how do the brightnesses of the 2 LEDs compare? D1 D2 PSB + Red Red 5 V R1 220 Q O It depends on the arrangement of the circuit. The brightness of D1 is greater than the brightness of D2. The brightness of D1 is approximately the same as the brightness of D2. The brightness of D1 is less than the brightness of D2.Question 2 3 pts Consider the brightness of each of the LEDs when two red LEDs are connected in series with a resistor and a shorting wire is connected across the second LED, as shown at D2 in the schematic below. Select all three of the following statements that apply. D1 D2 PSB + Red Red 5 V R1 220 Q O The brightness of D1 is greater than the brightness of D2. O D1 is brighter than it was before the shorting wire was added. O D2 does not visibly light. O D1 does not visibly light. O The brightness of D1 is less than the brightness of D2. D2 is brighter than it was before the shorting wire was added. O The brightness of D1 is approximately the same as the brightness of D2.Question 3 6 pts Consider how the circuit was effected by adding a shorting wire across D2, shown in the schematic below. Compare the color-coded schematics you were instructed to make in Steps 1 & 2. Select the best answer to each question below. You may collect further evidence to support your answers by using your voltmeter to measure the voltage across each component both before and after the shorting wire is added across D2. D1 D2 PSB Red Red 5 V R1 220 Q a.) How is the voltage across each of the components in the circuit changed when the shorting wire is added across D2? [ Select ] b.) How is the flow of current changed in the circuit by adding the shorting wire across D2? [ Select ] Select The path followed by the current no longer includes D2. Current is disproportionately redirected away from previous areas, where the energy is dissipated as excess heat. The current is the same as before, but D2 is no longer affected by the current and does not light up. c.) How does D2 affect the circuit after the shorting wire is added, as shown in the schematic D2 is burned out, because the shorting wire has almost no resistance.Question 3 6 pts Consider how the circuit was effected by adding a shorting wire across D2, shown in the schematic below. Compare the color-coded schematics you were instructed to make in Steps 1 & 2. Select the best answer to each question below. You may collect further evidence to support your answers by using your voltmeter to measure the voltage across each component both before and after the shorting wire is added across D2. D1 D2 PSB + Red Red 5 V R1 220 Q a.) How is the voltage across each of the components in the circuit changed when the shorting wire is added across D2? [ Select ] b.) How is the flow of current changed in the circuit by adding the shorting wire across D2? [ Select ] c.) How does D2 affect the circuit after the shorting wire is added, as shown in the schematic above? [ Select ] [ Select] D2 is still a red LED. Since the component has not been changed, its effect on the circuit has not changed. D2 uses more energy than before. D2 is no longer affecting the circuit. D2 has turned off, forcing current to flow through the jumper wire instead.Question 3 6 pts Consider how the circuit was effected by adding a shorting wire across D2, shown in the schematic below. Compare the color-coded schematics you were instructed to make in Steps 1 & 2. Select the best answer to each question below. You may collect further evidence to support your answers by using your voltmeter to measure the voltage across each component both before and after the shorting wire is added across D2. D1 D2 PSB + Red Red 5 V R1 220 Q a.) How is the voltage across each of the components in the circuit changed when the shorting wire is added across D2? [ Select ] Select] Voltage across D1 remains the same (red). Voltage across R1 also remains the same (blue). Only the voltage across D2 has changed (from orange to yellow). There is no longer voltage across D2. That voltage is now added to D1, which lights more brightly as a result. b.) How i D2 now has the same color on both sides, showing that there is no voltage across that LED. The total circuit voltage is unchanged, so the voltage across the other components is increased The PSB setting is unchanged, therefore the voltage across the circuit remains the same (5V). c.) How does D2 affect the circuit after the shorting wire is added, as shown in the schematic above? [ Select ]Question 4 3 pts What did you predict would happen if you shorted D1 instead of D2, and why. Remember that a valid prediction must include the reason for the expected outcome. Edit View Insert Format Tools Table 12pt Paragraph B IYA Q V T V V EVEV TO VX I P 0 words >Question 5 3 pts When you shorted D1 instead of D2, did the observed results match your prediction? If not, what differences do you observe and how might they be explained? Edit View Insert Format Tools Table 12pt v Paragraph BIUA &V T V 8 v EVEVEV TO BV VX H P O words > ::::Question 6 4 pts Why did the LEDs in this lab not burn out when they were shorted? Your explanation should include descriptions of what happens to the voltage across an LED and the current through that LED when the LED is shorted. This explanation should also become part of your own mental model of how circuits work. Edit View Insert Format Tools Table 12pt v Paragraph v B I U A & v TV V Ev Ev To V Vx H p O words >