Resistors

This is a really long confusing unit. We've learned about resistors. In a series, more resistors means more resistance. In parallel, more resistors means less resistance. It's a mathematical thing.

Series: R1 + R2 + R3 = total resistance
Parallel: 1/R1 + 1/R2 +1/R3 = 1/total resistance

See how that works out? We've also been getting into hectic stuff. Scientists are crazy. Anyway, the extra practice and repetition for this class has been really helpful. To sum everything up, in series, current is the same throughout the entire thing, while the voltage of the resistors when added together create the voltage of the source. In parallel, the sum of the current through each resistor is the current from the source, and voltage across each resistor is the same.

Also, to find the I(batt), total voltage must be divided by equivalent resistance.

Finally: Electricity Challenge

On my way home from school I told my father about the electricity challenge. He agreed, but didn't think that I would succeed. You might wonder why. Last month, I was staying with my mother, who lives separately from my father. This month is the first month in a while that I am staying with him; therefore, it will be difficult to reduce the electricity usage when another person is in the house. However, I will try.

Unfortunately, I know some major ways that we could save electricity...at the cost of my grandmother's convenience. We have two lights and a tv that are ALWAYS on for her. I think my brother and father also feel sympathy for her because she is older and has a difficult time getting around, so we always end up leaving those things on for her so she has something to do and so she doesn't trip or fall.

Anyway, I will be trying...

Resistance and Current

Resistance is the opposition to the flow of charge. Without electric potential or voltage, charge (that is, the electrons) will not flow. The energy change is instantaneous, but the change of charge is slower but eventually gets there.


However, thanks to ...Ben Franklin, we say that the positive charges flow...in a sort of system I can only understand that makes him seem right...


A resistor is anything that resists the flow of charge. A lightbulb is a very common example of this.Resistivity is the resistance of an object. It is shown by the equation:    R = (ρ *length of material)/A
It is measured in ohms, with an upside-down horseshoe-looking thing. In a schematic diagram, a resistor is represented by a cluster of sharp points that resemble a heart monitor line. This is a picture of the symbol for resistor. I figured I might as well show it because I already have pictures of my lightbulb in this room up.


Moving on, current is the number of charges that passes a point per second. DC, direct current, has a one way charge. Alternating current, AC,  has a two way charge. Yay for allusions in real life! 

Capacitance

Capacitance is short term energy storage. It can store lots of voltage, but not a great deal of charge. Capacitance is measured in Farads.

EoA
-------  =  C
d

Eo is "epsilon," the permativity of free space...air. It's usually a constant--> 8.85*10^-12 in Coulombs squared divided by Newton Meters squared. The A represents the area of the plates and the d represents the distance between the plates. Thus, A is related directly to Capacitance and d is related inversely.

This keyboard apparently uses capacitance to allow everyone to type whatever they wish. Pressing the key of the letter you wish to type decreases the distance and sends a signal that then allows that letter to be transferred to the screen from the keyboard.

Somehow, I felt that this picture would fit the blogpost.

Electric Potential

Electric potential is the amount of electric potential energy divided by charge. The equation looks like this:

PE(q)
-------- = V
q

Another name for electric potential is voltage. A volt is in Joules/Coulomb, so when the two are seen together in a physics problem, this equation might help! However, it should be noted that electric potential and electric potential energy are two entirely different things. Electric potential energy is the amount of stored energy of a charged object in an electric potential field...Anyway, it is in Joules whereas electric potential is in Joules/Coulomb.

My calculator here takes up 4 triple A batteries with 1.5 V each. Apparently, with some rewiring, we could make the calculator run on a larger, heavy duty battery instead of the tiny ones. The difference would be the endurance of the batteries and the convenience. (Who wants to carry around a bulky calculator?)

Charges.....Again

Unfortunately, this is a chapter about which I don't comprehend much. I tried reading the book and reviewing the exercises, but the more I read, the more I felt I didn't understand...Luckily, this past week helped a little bit more. Not as much as I would have liked, but it was okay.

Newton's Law of Gravitation is as follows:

F(gravity) = G(m1+m2)/2^2

It is really similar to Coulombs Law or something...in which k = 9*10^9

F(e) = k(q1q2)/r^2

Another equation I got from my friend is  E = F/q. And q = ne. I'm not really sure when to use either, but maybe adrenaline during the test will help me think...Anyway, the review worksheet we were given sort of helped. It reminded me that electrons are the things that exchange as opposed to the neutrons and protons.


...And this is attraction at its best.

Charges

So I'm sure everyone has heard that "opposites attract." Regarding people, this does not always hold true. It does sound logical, but so does "birds of a feather flock together." However, because physics is not the same as psychology, the former line holds true for us.

There are three types of charges: positive, neutral, and negative. Positive and negative charges attract. Neutral and any charge save for another neutral charge attract. Same charges repel, again, with the exception of neutral charges. When there are two neutral charges, they do no react in any way.
(These make fun brainteasers.)

In class, we had to experiment with tape. Gabe and I worked as a pair to deduce whether or not certain pieces of tape had different charges. It was pretty cool, considering that I've never played with charged tape...or tape at all...


...The deer were all attracted to him.