The fundamental parts of electricity are charges.
When an object is polarized, it means that one side of the charges have moved to one side of the object. That is, all the positive charges would have moved to one side, and the negative to the other so that one side of the object is positive and the other is negative, but the object is still neutral.
One kind of charged electricity we talked about was Static Electricity.
There are three ways to charge something:
1.) Through Friction (by rubbing two things together)
2.) By Polarization. The way this works is that you bring an object over that is of either - or + charge and it attracts the opposite charge and repels the like charge. An example of this is when a balloon sticks to a wall. First you charge the balloon (-) using the aforementioned friction, then when you put it on the wall, the + attract and because the distance is less that the distance of the - charges repelling, the force is greater and the balloon sticks.
3.) Through Induction. Induction is similar to polarization in that you basically use a charged rod in the way of the balloon to polarize and object and then separate the two sides and you have two charged objects.
This image helps visualize it a little:
I mentioned before that a balloon sticks to a wall because of the distance between charges. This is because of Coulomb's Law which is....
F=kq1q2/d^2
Here the k is just a constant, and the two q's stand for charges. The force and distance are inversely (square) proportionate, so when the distance is lesser the force is greater and vise versa.
The Force that is push and pull of charges is caused by Electric Fields. - which is the area of influence (push or pull) around a charge. Basically, the energy is stored in the electric fields.
The way you draw the electric field of a charge is by drawing arrows out from it indicating which way a positive charge would go. here is an example:
Electric Fields facilitate Electric Shielding. This is the reason we have metal casings around electronics, it protects the charges from being influenced by outside charges in the world. It works because the metal shield pulls the charges inside all around, and the pulls from one side cancel the pulls from the other, and the charge inside feels no force.
We did a podcast on Electric fields, here it is:
So, the Electric Fields hold the energy of the charge, the potential of this is called Electric Potential, which is the potential energy per charge. We call this Electric Potential Volts.
We represent that as this formula: V=PE (potential energy)/ q (charge)
When we have a difference in Volts, it is called Voltage. Sometimes we have something with high volts and something with low volts and the energy wants to travel from the High voltage to the Low.
This flow from high to low completes a circuit, and when the circuit is complete, then the energy is compelled to run through.
This flow of energy is called Current (represented with an I).
Ohm's Law defines the relationship between Current and Voltage:
I=V/R
The I is current and the V is change in Volts, but the R stands for Resistance. which are measured in ohms (the symbol for this is an omega sign in greek).
Resistance is something that is put in circuits to regulate the current despite what the voltage is.
Every normal outlet has a voltage of 120V, but appliances change their receptive currents for whatever the appliances needs are by adding resistors.
When you look at the equation, you can tell that the resistance and current can change but keep the voltage the same. The same is true for current. You can keep current the same, but still make an appliance more or less dangerous by increasing the resistance. for instance 5/10 and 2/4 are both equal to .5 (that would be the unchanged current), but the volts are 5V in one and 2V in another by increasing the resistance.
The first box on this website explains resistance well and you can enter numbers to play around with how they all relate.
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmlaw.html
There are two types of current: AC and DC
AC is alternating current, that is when the electrons move side to side as energy
DC is direct current, which is when they move forward.
There are a couple of things that affect current like
a.) thickness of what is traveling through. Thicker=more conducive
b.) Temperature- cold is better
c.) length- a short wire/tube is better
When we talk about actual circuits in places, often the circuits are parallel. What this means is that there are several appliances hooked up to a voltage source, and while they are hooked to the same source, they can operate autonomously. The alternative to this is a series circuit, which is set up to where each thing hooked up gets its current through the previous thing so, if one goes out they all do. Think christmas lights.
This is a great picture of what that looks like:
A parallel is preferable because you can turn one thing on without having to turn everything on. But, because on a series, everything is connected to the same line going to the source, when you add something, the current goes down because they are sharing and the resistance goes up. But in parallel, when you add one, you must increase the current to accomodate.
To make sure that the current does't get too high and cause a fire or something horrible like that, we have fuses and circuit breakers. These will detect that the current is too high and break the circuit so that it isn't complete and the current won't flow
A fuse is the same as a circuit breaker in purpose, but simply a different mechanism.
to figure out the power you are using, you use the formula:
P=I/V which is measured in kw(kilowatts)/hr.
To figure out how much it costs all together, you do this:
Power x hrs x $ per hour
And that's what we learned about Electricity!
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