May
23

Password to access protected areas of this website

To access any protected areas of this website with physics content please look at the right-hand side of the graphic at the top of the page.  To access copyrighted UIL materials please contact me for your password.

Why have I done this?

In an effort to continue to make my content freely available to my students, parents, colleagues and other educators, but to keep “web-bots” from stealing content from this domain, I have embedded the password information into the graphic at the top of the webpage.  The password should open all publicly accessible portions of this site and you should only have to input it once and your browser will store it (unless you have extremely tight security settings on your web browser).  If you have any problems accessing course content or if the password does not appear to work, please contact me as soon as possible.

May
24

Fare thee well, class of 2014!

Ladies and Gentlemen of the class of 2014:

It’s been super fun.  Really.  I’m not a big fan of goodbye’s, but I would be in denial if I told you that many of us would meet, together as a group, once more on this Earth.  You have been an amazing class, and through all of the ups and downs we have shared, I have learned some things from you even while, I certainly hope, you have learned some things from me.  I hope that besides physics, you have learned to question and to think.  I hope that you have come to enjoy irreverent sarcasm as much as I, and I hope that you have come, or at least are coming to enjoy the beauty of our world that lies beneath the numbers.  We live in an elegant place and I am mystified and fascinated by its nuances, captivated by its chaos, and captured by its order every day.  You, now, get to play a part in that (because apparently when you are 18 the social order decrees that you are ready, regardless of whether you were before or won’t be until later).  Enjoy your lives.  Keep in touch when you can.  Hit me up on Facebook…yes, that makes me old, but sometimes you need more than 140 characters to say something, and its much less of a pain than cataloging all of your email addresses which will surely change over the next 10 years.  I think I say this every year (except for the “cheating year,” and I don’t really talk about them very much), but for right now, you really have been the best, most successful class that I have ever taught, and I am very proud of you.

AP Seniors 2014

May
24

PreAP Spring Final Exam Information

PreAP Spring Final Exam Information

 

May
19

PreAP multiloop circuit practice “quiz” KEY

PreAP–KEY–multiloop circuits quiz

May
18

PreAP Combo circuit example from class (hard)

PreAP Combo circuit example from class

May
18

PreAP Circuits HW 2, hints and helps

16:

You will construct a series circuit with the resistor you are given and another resistor, let’s call it X.  Draw a picture.  We know X has a value less than your given resistor (as per the problem) so we know the voltage across it is less than the that of the given resistor.  I’m going to be general since I am actually answer in this question for several people.  Let’s say you have a 6V battery and you need a 5V power supply.  What this means in practical purposes is that you need 5V across the given (larger) resistor.  The remaining voltage (1V in this case) will be across resistor X.  Use your values to find the current in your given resistor.  Since you have constructed a series circuit (a voltage divider) you can use this same current in resistor X.  You already know the voltage across resistor X is the difference between your power supply and what you needed (in this case 1V), so using your current and this voltage you can find the value of resistor X.

This is actually a common problem in the construction of electronics.  You need a particular voltage somewhere, but you only have a certain power supply.  This is the process you have to follow.

 

17c&d:

C: Since the hairdryer and the TV are plugged into the same outlet, this implies that they are in parallel (does your TV shut off if you turn off the hairdryer?  Hopefully not, although I do wonder why you are plugging your TV and hair dryer into the same outlet to begin with…a little odd).  So you simply need to find the equivalent resistance of the two items in parallel.

D: This is basically part B all over again, but using your equivalent resistance of the two appliances from part C.  You need count the contribution of resistance in the wires (for most people, 2-3 Ohm’s) once.

 

22:

The problem mentions two batteries in series.  This is essentially what you did in the Ohm’s law lab by adding batteries to a circuit.  It is what you do when you put two batteries in a flashlight, or four in your calculator.  By placing batteries in series (facing the same direction) you are providing additional increases in electric potential to the circuit than a single battery.  In this case, you have two 1.5V cells, giving you have 3 total volts, and therefore TWO times the internal resistance stated, plus the resistance of the bulb given in the problem.  A and B are easy.  Use ohm’s law to find the current (part A) and P=IV to find the power (part B).  Part C is the part I mentioned in class that is acting strange in webassign.  All you should have to do is get rid of the internal resistance mentioned in the problem and re-do parts A and B and find the difference between your original and new value, but webassign is spitting out 90% of the correct answers.  Treat the “internal resistance” of the batteries as a small resistor (each) in series with the rest of the circuit.

Apr
23

PreAP: E-fields & Forces worksheet KEY

Worksheet–KEY–PreAP Efields Forces

Apr
16

AP: Magnetic Induction Quiz Problem KEY

B-induction problem KEY

Apr
14

Optics quiz KEY–2nd attempt

PreAP-lenses-mirrors-quiz-KEY

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