q42985           

I am a little confused with the amplifier stuff we are covering.  Right now, we are covering the components of an amplifier in depth.  Hopefully, we will tie all the components together and make sense on a whole of what an amplifier does.

I hope the final class brought it together.  While we will summarize materials on Tues, you would do well to drop by help session or office hours if you're confunsed.

I think the reading quizzes are bunk. I read the material in the book for the last reading quiz about amplifiers, reread the stuff that I didn't understand, and still only got one out of three right on the test. The one I got right was the one that everybody who read had to get right. Anyway, after the lecture I understood the material a little better. However, the book is basically worthless in my opinion, unless it's just for a quick reference like the definition of something (ie a step down vs. a step up transformer). I will now stop ranting and offer a possible alternative; maybe we could have a "reading test" at the end of class after we've "previewed" the material in the book AND recieve explination or further clarification from lecture. What think you?   

Neat ideas... I'll consider changing things around. However, you are responsible for reading BEFORE class and I want to make sure that happens....

I was a little confused on one area of todays(2/10) disscusion.  When we are talking about energy bands, which one is the valence band and which one is the conduction band in relation to the empty and full bands?

the top band is generally called the conduction band. The last band that is full is the valence band.

On homework #4 I think that one of the questins was graded wrong becuse I worked with you on it.  The question is true or false To produce a lower pitch tone, the speaker must oscillate back and forth fewer times each second.  I am reasoning through this and all I got is that pitch is directly related to frequency.  So if there are less oscillatoins per minute the frequency is lower which means that the pitch would be lower.  But where did my reasoning go wrong.

your reasoning is correct. but also the hw was graded correctly.

(1) It's one thing for people to come into class late, but it's another thing for people to come into class late entering through the front door and disrupting lecture.  There's one girl in particular that is always 10 minutes late and disrupts when you're already nearly 10 slides into your lecture.  It's really annoying?  Can you make a back-door policy for late students?(2)  Okay so eventhough I didn't feel like you went fast in class, the concepts for this week were really hard.  You explained them well but the consensus at the help sessions was that no one really understood what was happening in capacitors or transistors.  Nevertheless, I think the explanation of diodes was AWESOME!  I did not understand the book's explanation of this, but your class description and slides were sooo helpful!  Thank you so much!-

a) we have a new late policy -- thanks

b) thanks for the feedback. We'll review Caps and transistors again on Tues in review... but do come to help session / office hours if ya'll have further questions.

Professor Finkelstein,I really appreciate the homework correction essays because they allow me to consider past mistakes and make it possible to gain points for them. 

glad to hear.

I thought this past week's material was the most difficult of the course so far.  I understand transistors and diodes fairly well, but I'm still confused about capacitors.  I still don't completely understand how they allow a complete a circuit when no electrons can flow inbetween the two plates.  I also wanted to say that Akiko is very helpful at the Friday help sessions, and shows a great deal lof patience when we're stuggling to understand a concept.          

  good question. Technically there is no completion of the circuit and hence for DC current after a momentary flow of current the capacitor fills up with charge and allows no more to pass--- NO CURRENT passes through the capacitor. If however, the current alternates, this transient effect (filling up) changes to empting out... this filling up and emptying out continues to happen back and forth because of the AC. Now if one side of the cap fills up, so will the other (because opposites attract right? Thus one side constantly changing affects the other side.... Caps are good for AC and bad for DC.

I thought that lab this week was really interesting.  The labs are a great way of learning the material in the lecture.  It is one thing to just learn from the lecture, but when we are able to play around with materials and we see the priciples from the lecture in real life it helps us remember better. 

excellent. keep up the good work.

I have a question that may not be related to what we are studying this week, but it might be related to last weeks stuff.  I was watching T.V. over the weekend and saw an advertisment for a sodering tool called the Cool Heat or something like that.  They claim that it is hot when it touches other metal and soder, but it cools down within seconds of not touching these items, so it is cool to the touch.  I was just curious how this might work, if it has something to do with a semiconductor or what.  A semiconductor is about the only conclusion that I could come to, but at the same time, if it is, how is the semiconductor activated?  What is the medium that allows the electrons to move? 

  Hmmm... I don't know... there are a couple mechanisms by which this could happen... neat thinking on your part. I suspect it senses whether or not what you are soldering is conductive... if it is conductive it heats, if not, it won't (that is you want to heat up metal not your hand). It may also have a very high heat conductivity so it heats/ cools rapidly.. it might be interesting to follow-up.

I want comment again on how the repetition in this class is really helpful.  For example, we've been talking about things that have to do with the attraction and repulsion of charges.  There's a lot more than that, but there is a similar principle behind a lot of the things that we've been talking about.  That is really helpful because repetition is how people learn a concept and don't forget it.  ... I am doing what I can in this class, but it's not 100% student effort.  The teacher needs to be able to help the student reach her academic goals.  

Glad to hear going over material is helpful. As for your concerns about supporting your learning, rest assured I we have a LARGE number of people working on this cousrse and working pretty hard. To accomodate students I have not one help session but attempt to have 3. Sometimes it doesn't work out. The university has officially scheduled zero for you.

Last semester james gave test reviews during class on the day of the test.  They were VERY helpful.  A review from a student just works that much better.    

I'll ask if he's interested / available.

I thought the lab was a little long for the time we have. most of us didn't get to the last part, and i felt rushed as a recorder to get down everything we covered down and coherent on paper. it was interesting and fun, just not enough time.   

 Right... we'll work on this once again... I know Chandra is taking this into account in grading.

I thought the test last week was very fair and a good legnth. I was concerned a little bit with the third essay question. I didnt feel that we covered this topic in class as well. In the future will our essay questions on the test be this in depth (i guess)or will it be something like the other two which we covered directly in class?  

   I'm not sure which test version you're refering to... but glad the test went okay... generally I expect you to take the ideas from class and know them well enough to apply them to slightly different situations. That is our goal in understanding these concepts...            

Overall i thought the test was very fair, and i did like the more relaxed environment, it really kept me from freaking out and blanking.  Still some of the questions were a bit too reliant on tricky wording. perhaps we can discuss in class what you mean by some phrases like "very hard"  overall good test though      

            Cool. The exams are suppose to be low stress.. adn I'll work hard on the upcoming exam to make sure hte phrasing isn't too ambiguous.