The Physics of Electric Circuits

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The Physics Of Electric Circuits
Kevin Chang
Physics 212
4/20/15

What is an electric circuit?
An electric circuit is a closed path where there is a power supply measured in Voltage that allows electrons to flow from the negative terminal to the positive terminal through an insulated conducting wire powering one or more device. (Devices are consider resistors in a circuit such as: Light bulbs, microwaves, refrigerator...etc.)

What is the importance of understanding electric circuit?
1. To understand the relation between voltage, current, resistance, and power
2. To calculate your monthly electricity bill
3. To calculate the particular cost of a device in your monthly electricity bill
4. To build your own little circuit
5. Wiring up your own cabin
6. Calculating the internal resistance of a battery
7. Understanding transformers, fuses and circuit breakers
8. Calculating whether or not a resistor will blow up if plugged into the wrong
    power source

What are Electrons?
Atoms are the basic building blocks of the human world. Everything is made up from atoms. Atoms consist of protons, which are positively charged particles, electrons, which are negatively charged particles and neutrons, which are neutral. In the physical orientation of the atom, electrons are freely spinning around the atom as shown below. When a bunch of atoms are together they form materials. In metal, we have a bunch of electrons that are freely spinning around. When making a closed circuit out of metal, the freely spinning electrons have a flow in direction caused by the voltage of the battery which we then call Electricity.
                                         Atom





















http://www.ducksters.com/science/atom.gif

More about electric circuit:
A common electric circuit is usually composed of wires, switches, light bulbs, and a battery. Wires are considered the conductor in a circuit, which allows electrons to flow from the battery into the devices. The devices are considered resistors in circuits. Switches are considered current paths because you can turn a circuit on or off which causes it to become a open or closed circuit. A closed circuit will have no electrons flowing meaning that the circuit will do nothing. The battery is the power source that feeds electrons into a circuit.

There are three different types of electric circuits: series, parallel, and a combination of both series and parallel circuits. Finding out which electric circuit to use in different applications may be helpful because there are pros and cons to each type of circuit. To understand how the different types of circuits work and the relationship between them, you first have to understand how Ohm's Law and Kirchhoff's Law work.

Series Circuit
A series circuit is a combination of one or more devices hooked up by insulated wires in a way that the current measured through each resistor is the same.
 
Example of Series circuit:
This is a series circuit consisting of 3 light bulbs which act as the resistor, a battery that acts as the power source and the wires that act as the conductor.
As we can see from the picture on the left, the electrons move from the positive terminal to the negative terminal, which is not the case. In actuality, electrons move from negative terminal to the positive terminal. The reason why the diagram shows that electrons move in that direction is because we are taught to assume that is how it is and because calculating the circuit with Kirchhoff's Law
is much simpler.






Parallel Circuit
Parallel circuits are a combination of one or more devices hooked up by insulated wires in a way that the voltage is the same across each resistor and that each device hooked up completes its own circuit independently.

Example of parallel circuit:
This parallel circuit
consists of 3 light bulbs which act as the resistor, a battery that acts as the power source and the wires that act as the conductor. source.http://www.cdn.sciencebuddies.org/Files/4889/7/parallel-circuit-diagram_img.jpg

Series and parallel circuits are a combination of one or more devices hooked up by insulated wires in a way that some devices have the same measured current through each resistor and that the other devices have the same voltage across the resistor and also completes its own circuit independently.

Learning electrical systems and how transformers, fuses, circuit breakers and the different types of circuits can lead to future projects such as wiring your own house one day.