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That’s a correct statement. The answer choices we give you for that question aren’t quite so detailed, but I think you’ll know which one is correct.
Right! So, you can only assume there will be some kind of start device, but not which type. The correct answer has to do with the type of windings that all split-phase motors will have.
Is the only start device a PTC type?
Right, which of course wouldn’t be that big of a deal with other types of appliances, but no one wants to risk their food spoiling just because of a nuisance trip.
We describe this in the first video during the section on PTC start device failure (starts at about 21 minutes, 25 seconds into the video)
You are correct! Good job!
Hi John!
Yep, this is just a matter of getting the terminology straight.
We should always refer to parallel circuits, plural. Each branch is a circuit with one or more loads. If loads are in parallel with each other, they are technically in different circuits, even if they are tied together at some point.
Does that make sense? You can tell if loads are in series or parallel with each other by doing the Zen Trick.
If two loads are in parallel, will the current be the same or different through them?
Yep! I just wanted you to see how Ohm’s Law equations can be used to think through these things when you aren’t sure. But a fuse is basically a switch, and therefore acts like a wire (essentially no resistance, thus no voltage drop), unless of course it blows open.
I wrote my response only having seen your 69.99 answer.
The 0.014 is perhaps correct. Isn’t that essentially zero?
Rt would usually designate the total resistance for a circuit. We’re just concerned with the fuse.
I didn’t say your answer wasn’t correct, but I want you to KNOW the answer, not just guess.
You need to think about what a fuse is. Is it a load with resistance? What is its role in a circuit?
That’s right – and what would R (the resistance) be for a fuse?
Hi Bryan,
Let’s check your answer with an equation. What is the typical Ohm’s Law equation that we would use to find voltage?
Hi Heath,
Unit 5 is describing various characteristics of series circuits and parallel circuits.
When two or more loads are in series, you can add the resistances of the loads together to get a “total” resistance. This can be useful when calculating the circuit current, since the “total resistance” is what determines that.
However, when loads are in parallel with each other, we talk about “equivalent resistance”. It’s a similar concept – it’s a way of describing the overall resistance that is present from all of the loads combined. It’s more complicated than simply adding them together, however.
We show the formula for calculating equivalent resistance in Unit 5. But we also give the rule of thumb in the 3rd video in that unit (you can even see it in the thumbnail for the video!). That’s perhaps more important to know than doing the actual calculation.
Take a look at that information again in Unit 5, and see if you understand it. Let me know!
Hi Myles,
It could be, but we aren’t asking for that level of diagnosis in this question. You don’t have enough info to be that specific.
We tell you in the problem statement: *NOTE* These are simplified diagrams. There may be other components in the circuit that aren’t shown.
This means your answer will be a more general conclusion about the nature of the failure, not exactly which component in the entire circuit is bad.
What we want is for you to tell us what you can determine about the failure first from the measurements in Figure 1 (with the additional knowledge that the element has continuity), and then how the measurements in Part 2 give you even more insight into where the problem lies.
Back to your question – what is the basic thing that zero Vac across a good load tells you?
If you got the answers correct, they will add up to 120 vac (or perhaps 119, depending on how you rounded the number for current). Because the sum of the voltage drops of loads in series will always add up to the source voltage.
You should have a copy of the Ohm’s Law chart handy whenever you are taking a quiz or exam! (Or, just open the site up in another window so you can have that unit available to look at when you need it.)
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