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Voltage Divider Circuits
37 questions By Tony R. Kuphaldt
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Question 19 of 37
Calculate both the total resistance of this voltage divider circuit (as ßeen” from the perspective of the 25 volt source) and its output voltage (as measured from the Vout terminal to ground):
Note that the two 5 kΩ potentiometers are set to their 80% positions (m = 0.8), while the 100 kΩ potentiometer is set exactly to mid-position (50%, or m = 0.5).
Reveal answerRtotal = 9.762 kΩ
Vout = -16.341 V
Notes:Ask your students to explain why the output voltage is expressed as a negative quantity. Is this important, or is it an inconsequential detail that may be omitted if desired?
Also, it might be good to ask your students to show the equivalent circuit (made up entirely of fixed resistors) that they drew in route to solving for total resistance and output voltage. Encourage them to take this step if they have not already, for although it does involve “extra” work, it helps greatly in keeping track of the series-parallel relationships and all calculated circuit values.
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Question 20 of 37
Calculate both the total resistance of this voltage divider circuit (as ßeen” from the perspective of the 25 volt source) and its output voltage (as measured from the Vout terminal to ground):
Note that the upper 5 kΩ potentiometer is set to its 20% position (m = 0.2), while the lower 5 kΩ potentiometer is set to its 90% position (m = 0.9), and the 100 kΩ potentiometer is set to its 40% position (m = 0.4).
Reveal answerRtotal = 9.978 kΩ
Vout = 12.756 V
Notes:Ask your students to explain why the output voltage is expressed as a positive quantity. Is this significant, or could it be properly expressed as a negative quantity as well? In other words, is this an absolute value of a voltage which may be negative, or is it definitely a positive voltage? How may we tell?
Also, it might be good to ask your students to show the equivalent circuit (made up entirely of fixed resistors) that they drew in route to solving for total resistance and output voltage. Encourage them to take this step if they have not already, for although it does involve “extra” work, it helps greatly in keeping track of the series-parallel relationships and all calculated circuit values.
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Question 21 of 37
Which voltage divider circuit will be least affected by the connection of identical loads? Explain your answer.
What advantage does the other voltage divider have over the circuit that is least affected by the connection of a load?
Reveal answerThe divider circuit with proportionately lower-value resistors will be affected least by the application of a load. The other divider circuit has the advantage of wasting less energy.
Notes:Some students may be confused by the lack of a resistance value given for the load. Without a given value, how can they proceed with any calculations? Ask the other students how they solved this problem: how did they overcome the problem of not having a load resistance value to work with?
Plus signs are missing from these questions and answers, such as in question 11, where the denominator of the voltage divider equation appears as “R1 R2 R3” instead of “R1+R2+R3”. Same in the answer to question 15. Likely elsewhere as well, as Find shows no results for “+” anywhere on the page. I’m using Chrome 88.0.4324.182 on Windows 10, but same on Firefox & Edge. HTML source for the page shows it as “R1 R2 R3”, so it isn’t just a display problem.
Iam a student and i need an explain for this answers how can I get an explanation ?
Ca any one tell in detail how
The formula got formed like this !! ( ER= Et(R/Rt)) thank you