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March 23, 2020 at 9:18 am in reply to: Final Exam Question that I’m just struggling to wrap my head around it. #18797
That’s exactly correct! Great job thinking that through.
March 23, 2020 at 9:16 am in reply to: Module 8 Unit 2 Variable Frequency Drive System Audio Problem #18796I’m glad you got it to work. Browsers are always changing, and we occasionally hear about random issues with a plug-in that we use. The solution is usually to try a different browser.
March 22, 2020 at 4:59 pm in reply to: Module 8 Unit 2 Variable Frequency Drive System Audio Problem #18787Hi Shawn,
It works for me. I had a student a month or two ago who had this problem, and tried a different browser and it played for him. What browser are you using?
Hi Shaya,
It is only on DC circuits that you have polarity (a positive and a negative side). If you are measuring voltage in a DC circuit, the result on your multimeter will let you know what the polarity is (if you get a negative sign, it means you’ve switched the probes).
In AC circuits it doesn’t matter where you put your probes. The current is rapidly switching back and forth, so there is no positive/negative side and the voltage reading will not indicate + or -.
Just make sure you’ve set your multimeter on the correct setting! (AC or DC voltage)
If a circuit has L1 and L2 as the two ends of its power supply, that is a 240vac circuit. That’s what we have shown every single time.
A 120vac circuit has line (usually L1) on one side and neutral on the other.
Hi Kellen,
Which question in particular gave you trouble? I see that you got them all correct on your second attempt.But, in general, we covered this type of material in Module 3, particularly in units 3 and 8.
Tell you what. If you can email me answers to the following questions, I won’t make you retake the whole exam.
Please email them to me (susan@mastersamuraitech.com) – don’t put them here.
Questions 24, 29, 58, and 61
He would have been referring to a closed switch having very little voltage drop.
Current flowing through a component with resistance creates a voltage drop. A closed switch has essentially no resistance. (It’s not absolutely zero, but for the circuits that we deal with in appliances, it’s close enough.) So for our purposes we would say it has no voltage drop.
An open switch has infinite resistance – no current is flowing – so the voltage difference across the switch is NOT voltage drop. It’s just regular potential voltage.
Hi Joe,
you are correct for #4 and 22.For #20 you’ll have to see the choices again and figure out which one is correct.
Yes – it’s fine. But that needs to be pointed out to the Appliantology administrator, so that he’ll know you are an enrolled student. I’ve forwarded your email to him.
Hi Shaya,
In a 120 vac circuit, you’ve got Line on one side of the load(s), and neutral on the other.
In a 240 vac circuit, you’ve got L1 on one side of the load(s), and L2 on the other.
They basically work the same way, there’s just a larger voltage difference between the two sides. The electrons still zip back and forth along the two sides of the circuit. Remember, in AC circuits, the current does not just go in one direction.
Does that help?
We don’t mean for it to be tricky. Techs need to keep current and voltage distinct in their minds. It should be as obvious as reading “apples and bananas” that current and voltage are describing very different things. So, it’s a lesson in paying attention to important terminology!
Question #2: Measuring DC current is a measurement you will probably never do as a professional appliantologist.
But based on what you said, if R1 is two times R2, and if R2 is 30, then R1 is 60. R1 + R2 has to be = 120. 60+30 = 90.
Hi Snoopy – that’s a bit more complicated than what we show in the Unit 3 “loose connection” video.
Micah – please watch that video and see if you can follow along the calculation, and let me know.
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