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June 5, 2019 at 8:45 am in reply to: Basic Electricity: Series and Parallel Circuits – Path of Least Resistance #15968
Hi Nate,
Great question! Yeah, that “path of least resistance” saying is problematic. It’s sort of correct, but not completely, which is why we don’t like it.
First of all:
And how does electricity know to follow the path of the shunt?
Remember that electrons don’t “know” anything. Fortunately for us, they don’t do independent thinking, and therefore follow consistent and predictable patterns 😉
Electrons will move in response to the presence of voltage if they have a complete circuit. When there are multiple paths available (parallel circuits), and if each path has a load in it, then electrons will move through all of those paths.
If the resistances are different in each of those parallel paths, then that will affect how much current each path gets. Lower resistance will result in higher current flow. (I = E/R, so as R gets smaller, I gets larger), and vice versa. But they’ll all have some flow, even if one of the resistances is significantly higher than the others. (This is why the “path of least resistance” saying is problematic – it sounds like all the current will flow in the path with lower resistance.)
A shunt is a pathway with zero resistance. In this circumstance, ALL of the electrons will go through this path, none will go through the circuits with loads, and we call it a shunt.
Does that help?
Hi Robert,
He is correct that the shunt bypasses loads D, E, and F. When the electrons come to that tie point on either side of the parallel loads, they can either go through one of the loads or go through the shunt wire – they are all tied together. If electrons have a route that they can take with no load in it, then they’ll take it 100% of the time!
70 ohms is the total resistance.
What is your second calculation? You gave the answer in “ohms”. Is that what you meant?
With calculations like this, it is good to write out the units and what you are trying to calculate, so that you can keep everything straight.
Hi Matthew,
The Final exam does not change like the Module exams do, which should make it easy to improve your score. I’m glad that you got over a 90% on your first attempt, though!
For Part 2, there are two attempts. It is open answer, so you have to wait for us to grade your first attempt, then you’ll get an email discussing your results (like you did with the Midterm).
As for study hints, the questions are all drawn directly from the course material, and are often similar to (or exactly the same as) some of the quiz questions. We ask for definitions, explanations, and some calculations.
Good luck!
Yes, 2, 3, and 4 are the same series circuit with 3 loads, and we give you the resistances.
Question 2 asks for the total resistance.
You know each individual resistance – how do you find the total? (The word “total” is a big hint.)
Answer that, then we’ll move on to the next question.
May 30, 2019 at 4:48 pm in reply to: How to find voltage drop if I don't know resistance of loads #15932Hi Steve,
Since you are asking about different types of calculations, and some of them are unrelated to this original post, I’m going to move your question to a new topic.
Steve – See the video in this topic: https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/calculating-equivalent-resistance/
Hello – no, the Final Exam does not include questions from the bonus modules.
Hi Tom,
We don’t have that available, but you can always take a screen shot of any of the slides that you’d like to have on hand.
Hi Tom,
Normally, it would mean rolling it away from the wall so you can reach the back. But, just to make sure I’m giving you the correct answer, where did you see that in the course?
Done!
Great! I’m glad you asked the question. Thank you!
Do you want me to reset that quiz so you can retake it?
Yes, P2-6 is a good test point for the L2 side of the element.
From the component ratings on the tech sheet, we would expect around 16 ohms resistance if the element is NOT open.
It sounds like you are trying to find two test points that are EEPs with each other, but that is not what we’re trying to do with EEPs. Each convenient testing point needs to be an EEP with one of the power supply lines to the LOI.
The two sides of the element are not EEPs. Any two points that have a load in between them are not electrically equivalent.
Do you remember the two criteria for EEPs?
Two points that
1. are in continuity with each other, and
2. have no voltage difference between them.You are basically looking for a wire that connects to the load of interest, with no other loads along the way.
You need to put your meter probes in two locations to measure the resistance. You are looking for two test points that will be electrically equivalent to either side of the element. (same thing if this happened to be a voltage measurement)
For example, you are correct that P1-1 is a good test point. A wire connects directly from P1-1 to one side of the element. P1-1 is an EEP for the L1 side of the element.
Now you need an EEP for the L2 side of the element.
Hi Travis,
You’ve already indicated in your previous answers on the quizzes that you are trying to measure resistance (ohms) of the load of interest – the upper bake element.
Your current answer on the unit 7 quiz is to use the test points P1-1 to P1-6. Looking at the diagram on the tech sheet, does that isolate the bake element?
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