March 28th-A Day of Physics

10:45 AM
*Mr. Wirth wonderfully volunteers me to be scribe. . .
10:47AM
*Begin going over the homework
Example work for #3-
Given Info:
q = 220 C
v = 220 V
t = 4 sec

ESA work:
P = VI
P = V [(delta q)/t]
P = (2200 C)(220 V) /(4 s)
P = 12,100 W

10:55 AM
*Begin notes
*Analyzing Circuits
-several different configurations
-branches
-involves Ohm's Law (applies to circuit and individual resistors)
***Equivalent Resistance: The Resistance Seen By The Source***
R(eq) = V(source) / I (source)

10:58 AM
*Talk about Next Week
-will apply these principals to several different circuit configurations
10:59 AM - 11:00 AM
*Talk about new cell phone policy and pass out the review set #1
11:07 AM
*Still working on review set
11:25 AM
*class ends; have a nice weekend :)

-DH

3/26/08 Class Notes

AC = alternating current. The flow of the current alternates direction
DC= direct current. Only flows in one direction
We will only be working with DC.

Current (I)= the flow of an electric charge. Unit: ampere (A) or coulomb/second.
The equation for current is listed in the reference table as I=(change in q)/(t)

Potential difference (V)= the driving force behind causing a flow of charge.
SI Unit: volt (V)
1 V=1 J/C
The equation to find V is V = W/q

Resistance (R)= oppostition to the flow of the current. It measures the degree and object opposes a current
SI Unit: ohm (theres a funky symbol in the reference table for it) which was named after a German physicist

Ohm's Law: At Constant Temperature, The Current In A Metallic Conductor Is Directly Proportional To The Potential Difference Between Its Ends.

The equations for Ohm's law are as follows... R=V/I....I=V/R.....V=IR
1 ohm = 1 Volt/Amp

We did two exaples in class and then worked on homework for the time we had left.

3/25/08 Notes

Electrical Circuits:

• Closed loop or path
• Consist of charged particles that move
• An electrical current can exist
• Are formed by a source of potential difference and includes one or more resistances

Circuit Elements:

• Source elements - device or system that can produce a potential difference.
• Load elements - device or system to which the source is connected.
• Control elements - used to control the flow of electrical current.
• Path elements - used to interconnect other elements.

Circuit Symbols:

Current:

• The flow of electric charge.
• The time-rate at which charge flows past a given point in a circuit.
• SI unit: ampere (A)
• 1 ampere = 1 coulomb/second
• 1A = 1C/s
  
  

The Leyden Jar...Finally

The Leyden Jar is a capacitor, it stores electricity.  There is an electrode on the top of the jar, and a chain is attached to it.  The jar becomes charged by static electricity buildup in the inner electrode, while the outer part of the jar is grounded.  The Leyden Jar was used in early wireless technology.  

March 17th- class notes

In class we went over electrical potential, what a volt is and uniform electric field. A volt is the SI derived unit for electrical potential. Electrical potential may be conceived as "electric pressure". Where this pressure is uniform , no current flows and nothing happens. This is similar to why people do not feel normal atmospheric pressure. However when this electric pressure varies, an electric field exists, which creates a force on charges particles.