ch 20 #63

During one of Franklin’s initial experiments he noticed that a pith ball or cork would be repelled if touched together but at would be attracted to a charged object. He realized this because the two objects were initially charged differently, but once they touched they acquired the same charge. He later realized if he replaced the charged object with a bell he could make an "electric bell." Later he used the bell as a lightning detector that became known as Franklin’s Bells. When the bell was connected to a lightning rod it would ring when an electrical storm was nearby, which could be used as an early form of weather detection.

The Leyden Jar is a device that was invented by Pieter van Masschenbroek in 1975 to store electric charge. The Leyden Jar was made of a glass bottle with water to act as a conductor for electricity. It was made with a metal wire that passed through a cork which closed the jar. The design of the jar later added a metal foil coating part of the inner surface and a conductor foil wrapped around the outside surface. The jar is also now charged by an electrostatic generator connected to the inner electrode, with the outer plate being grounded. Additionally, the inner and outer surfaces store opposite charges that are equal in amount.

4/1/08 Blog Post

Heyy, so today we started off by Mr. Wirth reminding to scribes to always be alert! Well this one obviously was, because I remember that we started off with a review sheet he handed us...

We did about 4 problems on the sheet that reminded us of the properties of this unit.
We calculated the amount of charge passing through resistor (R2) in 60 seconds. We did this by using I=delta q/T
Next we learned how to draw a parallel circuit using the ammeter symbol, battery, and 2 resistors of a certain ohm.
Lastly we calculated the equivalence resistance of the circuit by using the equation 1/Req=1/R + 1/R2...

After reviewing these concepts we jumped right into notes...
VOLTMETER: measures potential difference between two points in a circuit.
**these are connected in PARALLEL
**extremely HIGH internal resistance
**draws extremely SMALL current

AMMETER: measures current through ONE point in a circuit...
**connected in SERIES
**extremely LOW internal resistance
**creates extremely SMALL voltage drop


so that was all the notes did for the day... by the way ellen missed all of this because she was not here. so i hope she takes full advantage of this blogging experience...

ok peaceout

Chapter 20 Question 63

Leyden Jar
It is a devide for storing electrical charge and was invented in 1745 Pieter van Musschenbroek. It was the first capacitor and was used to conduct experients dealing with electricity. the design consists of an electrode connected to a metal foil folding part on the inner surface of a glass jar. The conducting foil is wrapped around the outside of the jar which is charged by an electrostatis generator, which is connected to the inner electrode and the outter plate is grounded. Both the inner and outter surfaces of the jar hold opposite charges. Originally it was a glass bottle partially filled with water with a wire passing through the cork that closed it. Benjamin Frankilin found out the charge was stored in the glass and not the water.
Franklin's Bells
During one of his initial experiments he noticed that a pith ball or cork would be repelled if touched together but initially would be attracted to a charged object. he realized this because the two objects were initially charged differently, but once they touched they acquired the same charge. He later realized if he replaced the charged object with a bell he could make an "electric bell." Later he used the bell as a lightning detector. When the bell was connected to a lightning rod it would ring when an electrical storm was nearby.