Monday, January 23, 2017

Week 3

Monday


1.) Compare the calculated and measured equivalent resistance values:

Figure 1: The pictures above give a visual representation of the circuit configurations accounted for in  the table below (Figure 2).

Figure 2: The table above shows the calculated and measured resistance values for each resistor along with the difference percentages between measured and calculated values.

2.).Apply 5V on a 120Ω resistor. Measure the current by putting the multimeter in series and parallel. Why are they different?

  • When measuring current in series a correct measurement of 41 mA was achieved.
  • When measuring in parallel the resistor was shorted and an incorrect value was measured for the current because when the resistor is shorted, it does not affect the current as it does when measured in series.

3.)Apply 5 V to two resistors (47Ωand 120Ω) that are in series. Compare the measured and calculated values of voltage and current values on each resistor.



Figure 3: The table above displays the calculated and measured current and voltage values for the two resistors in series.

4.)Apply 5 V to two resistors (47Ωand 120Ω) that are in parallel. Compare the measured and calculated values of voltage and current values on each resistor.

Figure 4: The table above displays the calculated and measured current and voltage values for the two resistors in parallel.

5.)Compare the calculated and measured values of the following current and voltage for the circuit below: (breadboard photo) 

a. Current on 2 kΩ resistor

  • Measured current for the 2k resistor was 1.6mA
  • Calculated current for the 2k resistor was 1.9mA

 b. Voltage across both 1.2 kΩ resistors.

  • Calculated Voltage for 1.2k (A) was 0.80 V.
  • Measured Voltage for 1.2k (A) was 0.80 V.
  • Calculated Voltage for 1.2k (B) was 0.74 V.
  • Measured Voltage for 1.2k (B) was 0.74 V.



Figure 5: Picture of our build of the circuit from Figure 7.












Figure 6: Different angle of the same circuit shown in Figure 7.
Figure 7: Picture of the circuits that were built above.

































6.)What would be the equivalent resistance value of the circuit above (between the power supply nodes)?

Based on our calculations, the equivalent resistance value of the circuit above (Figures 5-7) is 2.5 kΩ.

7.)Measure the equivalent resistance with and without the 5 V power supply. Are they different? Why?

  • Without the power applied the meter reads 2.56 kΩ. A resistance is given because there is no voltage, in this case the 5V, to disrupt the DMM.
  • With the power applied the meter reads OL(Overload). OL occurs because there is voltage from both the DMM and the power supply which interfere with each other.

8.)Explain the operation of a potentiometer by measuring the resistance values between the terminals (there are 3 terminals, so there would be 3 combinations). (video)

Figure 8: In the video above, the operation of the potentiometer is explained.

9.)What would be the minimum and maximum voltage that can be obtained at V1 by changing the knob position of the 5 KΩ pot? Explain.

Figure 9: Pictured is the circuit relevant to the problem.
When the potentiometer is set to 0Ω there's no resistance so there will not be a voltage drop. If the potentiometer is set to something other than 0Ω the max voltage achieved will always be 5v.








10.)How are V1 and V2 (voltages are defined with respect to ground) related and how do they change with the position of the knob of the pot? (video)

Figure 10: Pictured is the circuit being demonstrated in the video.
Figure 11: In the video, the relationships between V1 and V2 are shown.

11.)For the circuit below, YOU SHOULD NOT turn down the potentiometer all the way down to reach 0 Ω. Why?

Figure 12: Pictured is the circuit relevant to the problem.
Because there's no resistance through the potentiometer all the current will flow through it causing it to overload and be damaged.

12.)How are current values of 1 kΩ resistor and 5 KΩ pot related and how do they change with the position of the knob of the pot? (video)

Figure 13: In the video the relationship between the 1K resistor and the potentiometer is displayed with respect to the position of the knob.

13.)Explain what a voltage divider is and how it works based on your experiments.

voltage divider is a simple circuit which turns a large voltage into a smaller one. Using just two series resistors and an input voltage, we can create an output voltage that is a fraction of the input. Using the potentiometer as a voltage divider we saw that the voltage varied between the two channels as the resistance changed.

14.). Explain what a current divider is and how it works based on your experiments.

A current divider can be used to calculate the current through any branch of a multiple-branch parallel circuit. Current divider refers to the splitting of current between the branches of the divider. In our experiment with the potentiometer in parallel with the resistor we saw that the current differed as the resistance changed.

11 comments:

  1. It would help if you enlarged your table in Question 1, and also enlarged your pictures a bit so the breadboard can be seen more clearly. Also there is a small spelling error in Question 7 "Withe". Also it would help if you differentiated which 1.2k resistor was a and which was b in Question 5 b. Other than those few corrections looks good.

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    1. thank you for the feedback. We're trying to figure out how to make the table in question 1 bigger but it keeps wrapping to the next row. Also thanks for the spell check! that one got by us somehow

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  2. In question 2, it might be useful to include an explanation of the connection between shorting the resistor and obtaining an incorrect measurement. There is a similar issue with number 7, why were the readings different?

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    1. thank you for the feedback! i agree with both of your suggestions, those additions will definitely help.

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  3. Very good detail on your blog this week. I was curious for #1; what do you think caused the % difference between the calculated and measured?

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    1. i think it could have been because we were using 2W measuring instead of 4. Thank you for the feedback!

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  4. Your blog was easy to follow, and I liked how you guys included the original schematic Tolga gave us in the questions. I also like that you guys made the questions bold and in a different color than your answers.

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  5. Very nice, but for question 5, don't you think writing the equations that leads you to come up with these numbers is going to make it more clear?

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  6. #2: not quite correct
    Good interaction with your peers. Thank you.

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  7. Just realized "A voltage divider is a simple circuit which turns a large voltage into a smaller one." is plagiarism! NEVER AGAIN!

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