Shock Value B/Circuit Lab C

[liutony66]

6.002x is a course that MIT offered online through their edX program concerning Circuits and Electronics.

[iwonder]

Aww... Why didn't I hear about this

[Schrodingerscat]

6.002x? And it's not really too difficult, the wiki has a really nice section below each technical explanation of something the wiki calls 'the other analogy' that's really helpful in understanding basic electronics. Good luck!

It's not the basic concepts that make me nervous for the event, as I understand them fairly well, but it's some of the more advanced circuit analysis problems that I saw in the homework of the course.

[iwonder]

Ahh... The one that always gets me(my experience is more practical than textbook) is when they put multiple power sources in a circuit for analysis(not directly connected)... I've never seen that used in the 'real' world, so it always catches me off gaurd.

[iwonder]

Wow. That sounds like it was a fun course, but I'm pretty sure(and I've sen discussion about this before) that scioly specifically sets the rules so calculus and things of that nature never appear on the test, and looking at past years(my team has national tests dating back to 1993 or so, most of MIT's course material has never shown up... I only glanced over the MIT course, but after reading through a few national tests I never noticed anything beyond analyzing a circuit with more than one power source(still purely resistive) and some basic capacitor time curve problems in the SO tests. Of course, maybe they beefed it up this year...we'll just have to wait and see.

[Schrodingerscat]

Wow. That sounds like it was a fun course, but I'm pretty sure(and I've sen discussion about this before) that scioly specifically sets the rules so calculus and things of that nature never appear on the test, and looking at past years(my team has national tests dating back to 1993 or so, most of MIT's course material has never shown up... I only glanced over the MIT course, but after reading through a few national tests I never noticed anything beyond analyzing a circuit with more than one power source(still purely resistive) and some basic capacitor time curve problems in the SO tests. Of course, maybe they beefed it up this year...we'll just have to wait and see.

Yeah, I stopped actively participating in the course around the time they started to use calculus in the problems (although that wasn't the only reason, was just way too much extra work for during the school year for me). Although, as I look back at the homework, the applicable stuff does appear that it will be much easier with some practice.

[foreverphysics]

This event is making me nervous now...the only comfort I have is that both of my parents are electrical engineers with Ph.D's, so I can get all the help I need.

[space scientist]

I have a couple of questions about the 2008 Pennsylvania Regionals exam on the Test Exchange:

How do you solve number 2 on section 3 (I know how you could solve it if C6 and C10 were removed, but I don't know how to solve it with them in place.)?

Also on questions 3-10 on section 3:

3. Can someone confirm that the battery voltage is the limit of the graph as time approaches infinity?
5/6. How do you find the resistance of the resistor and capacitance of the capacitor?
7-10. When using Ohm's Law to calculate current, do you use the absolute value of the resistance plus capacitance (looking at it written in polar form) or the real portion of the resistance plus capacitance (looking at it written in written in rectangular form)? Furthermore, would you use R+C or R+|C| (if it is R+|C| then my previous question would be pointless)? (Really, I just don't know how to solve problems with reactive components when there are voltage transients (except for finding the time constant).)

Thank you in advance to whoever can answer these questions.

It should be exciting to do Circuit Lab this year (assuming that I make it on to the Seven Lakes team).

Edit: clarifying my questions

[iwonder]

Seven Lakes? Why would I help my competition Just kidding...

#2 For C10, you know that C9 and C12 are in series, once those are simplified the result is in parallel with C10. For C6 you have to simplify C's7-12 to one cap, which is then in parallel with C6.

#3 Yes, as the capacitor reaches a fully charged state it will approach infinite resistance, so the voltage across it will be the voltage of the battery.
#5/6 The value of the cap is given by (Capacitence=Charge/Voltage), and the resistance value is given by using the time constant (T=RC)
#7-10 Don't use ohm's law, and yes, you do need the time constant.

http://hyperphysics.phy-astr.gsu.edu/hb ... apchg.html

Also, what problems have you done that require reactance with DC? From my experience reactance and impedence are AC units...

Edit: Wrong equation

[sunje]

Hello all,

I am thinking about doing this event this year... but I haven't taken physics. Would physics be a tremendous help for this event or is it easy to self-study? Basically what I'm trying to get at is... if I self-study, would the kids in AP Physics still do better than me? I don't know how this event works at all.

Any input is appreciated. Thanks!!