Motor Blog

In class today, we learned how to build motor. Motors are used in our every day lives and it is therefore important to understand what it is. A simple motor consist of a battery, copper wire and a magnet. In class today we were given a rubber band, two paper clips, a long strand of copper wire, a battery and a magnet. The goal of this lab was to make the copper wire spin. This is accomplished by constructing a motor. The two paper clips are placed at each side of the battery and suspend the loop of copper wire over the magnet. The paper clips create a circuit that is closed when the copper wire is added. The magnet is placed below the copper wire, on top of the battery. When building this motor it is important to suspend the copper wire just over the magnet, not touching. When a current is sent through the copper wire, the magnetic field produced by the magnet, causes a force on the moving electrons. This is similar to cosmic rays trying to enter the earths atmosphere. The cosmic rays bounce off the earths atmosphere because it is perpendicular to the earth magnetic field. The electrons in the copper wire and deflected by the magnetic field since they are perpendicular  If the copper wire was parallel, it would not feel a force from the magnet. The magnet causes the copper wire to spin as long as there is a current running through the wire. It is vital to scrap the ends o the copper wire in a specific way. We scrap the copper wire to allow electrons to flow and to make the copper wire spin in a certain way. only one side of the copper wire is scrapped. Imagine the wire suspended over the magnet by the paperclips. The current goes through one side of the copper wire and is forced by the magnet to spin. If electrons went through the entire copper wire, it would spin back and forth since it would experience two equal and opposite forces.

A motor works because the moving electrons in the copper wire, experience a force from the magnet's magnetic field. This occurs because the copper wire is perpendicular to the magnetic field. The paper clips are used to suspend the wire and to complete the current from the battery to the wire. The rubber band is used to hold these two paperclips in place. motors are used in our everyday lives. It is used in our cars, in fans, in lawnmowers, practically anything. You can attach a fan blade on the end of the wire and create a fan. Its that simple!!

Magnets & Magnetism

Everyone loves Bill Nye and his explanations. In this video we are introduced to magnetism. The video explains that opposite forces attract and like forces repel. The video also explains what would happen to a magnet if it was cut in half. This is a very important concept that is normally overlooked by many individuals. I also found this video helpful since it gave real life examples of magnets in our world. The video does not explain magnetic fields and what they look like which is a very important concept to understand when learning about magnetism. This video does however, explain what magnets are made out of and that our planet is a giant magnet due to the spinning core.

http://www.youtube.com/watch?v=ak8Bh9Zka50

Electricity Unit 6

In this unit my class learned all about electricity. Everyone knows what electricity is but I had no idea why lighting occurs, how a fuse box works and how to make a balloon stick to a wall b rubbing it against your hair. I was exposed to many different phenomenons that occur in a our day to day lives but never really know how they work.

During this unit I learned how a battery, wires, and a light bulb fit together to make a light bulb work. A light bulb has an inert gas inside the glass. Also inside the light bulb is a filament  This filament is usually tungsten and is the part the electricity flows through. In order to light up the bulb with a battery and wires it is important to realize that the circuit needs to be closed. If there is any open space in the circuit then the electricity will not be able to flow. This is why a light bulb doesn't light up if the filament is broken. This means that the circuit is incomplete and the electricity is unable to travel through the system. In a circuit, a light bulb is referred to as a resistor since it uses electricity. Any appliance that is drawing energy is referred to as a resistor. If you jumped off the ground when you touch an electric fence will you get shocked? The answer is no, but don't try it! The electric fence will not shock you because the circuit is not complete, in order for you to feel a shock  you must be touching the ground. The reason you shouldn't try it is because when you get on the ground again and don't let go in time you will feel a shock. If you place a large enough insulator, such as styrofoam under your feet, you will not feel a shock. This occurs because the electricity does not go through the styrofoam therefore the circuit is not complete.

After this introduction into electricity we began learning abut charges. A neutral charge means that there is no overall charge. If something is negatively charged then there are more electrons present. If something is positively charged then more protons are present. We already know that like charges repeal and opposite charges attract (electrons attract protons but repel other electrons). Charges ten to move through contact, friction (two objects rubbing), and induction (a charge is made without contact). An example of friction occurring in our every day lives is when we wear socks and rub the carpet. This friction creates a negative charge in your socks so when you touch someone else and complete a circuit the energy travels through them and they will experience a shock. Induction is a little more complicated. Picture two metal balls both neutral and both touching one another. If you put a negatively charged stick towards one metal ball, the electrons in the rod will repel the electrons in the metal ball. Once the two balls are separated  one will be positively charged and the other will be negativity charged. Lightning is also an example of induction but on a larger scale. The molecules in a storm cloud create a negative charge in the cloud. This charge attracts all the protons on the ground until a path is created between the ground and the lightning. Although the electrons in the cloud is traveling to the ground, the immense energy produces light which is what we see as lightning. Interestingly more, lighting actually goes from the ground up, it just moves too fast for us to notice!

We also learned about polarization during this unit. Conductors allows charges to move through an objects and insulators stop charges from moving. Such materials such as rubber and styrofoam are insulators and metals are normally conductors. An object becomes polar when the charges are separated  The object is still neutral however the charges are separate. Why does ceran-wrap cling on to a bowl? When ceran-wrap is removed from the box the wrap becomes negatively charged due to the friction. When the wrap is placed on the bowl it becomes polar. The negatively charged wrap is attracted to the strong bond between the protons in the bowl. This makes the wrap stick to the bowl. Now, Why does ceran-wrap stick to the bowl when the other charges are repelling the negatively charged wrap? Columbs law states the force between any two objects is inversely proportional to the distance squared.
                                                            Columbs Law: K(q1)(q2)/d^2
The wrap sticks to the bowl because the distance is small between the two negatively charged bowl and wrap making the force small.
To answer this question we have 4 step to follow:
1 step: Plastic wrap is charged by friction and when brought near the bowl, it becomes polarized.
2 step: The positive charges in the bowl move close to the negative plastic wrap and the negative charges in the bowl move away from the wrap.
3 step: The distance between the opposite attractive charges is smaller than the distance between the like repelling charges.
4 step: Since there is a greater distance between the repulsive forces  the force between them will be less than the closer attractive forces. Thus the wrap sticks to the bowl.

Why are electronic devices always put in metal containers?
Many people, such as myself  don't understand this question until it is explained. In order to understand and answer this question we need to know about electric fields. An electric field is an area around a charge that can influence another charge. If a positively charged circuit board is placed in a metal container, all the surrounding charges will become equal and opposite and will therefore not influence the hard drive. It doesn't matter where this positively charged circuit is placed in the container, all the surrounding charges will have no influence with the charge and therefore the hard drive is protected. This is known as electric shielding  Another example of electric shielding occurs when lighting strikes a car. The individuals in the car will be safe in the car.

Voltage is the potential difference between two points. We calculate voltage by dividing electric potential energy by the charge.
                                                                    V= PE/q

During this unit we also learned about Ohm's law. This law states that current is equal to voltage divided by resistance. Current is the ability for electricity to travel through a wire. This is measured in amps and the universal symbol is I. Voltage is the potential difference between two points. Voltage is measure in volts and the universal symbol is v. Resistance is the tendency for a circuit to resist an electrical current and is measured in ohms. We can increase the current through an object by either replacing the material, making the  path wider or longer. Why does a light get dimmer? It is important to remember when answering this question that resistance doesn't change. If we have a 60W light bulb  and it starts to get dimmer, the voltage is decreasing. Which light bulb offers more resistance, a 60W bulb or 120W? this question is a little tricky. The answer is the 60W bulb. The 60W bulb has a shorter, and thinner filament therefore increasing the resistance.

When talking about circuit there are two that we use. One circuit is called a series and another is called parallel. Think of a circuit as a roadway system. A series circuit means that there are multiple red lights on one road. These red lights cause the traffic flow to move slower. In a series circuit, the more appliances are added, the less current is available. This is due to the increase in resistance. In a series circuit if one appliance is removed, the circuit is open and therefore all the appliances turn off. A parallel circuit can closely resemble a rod with multiple routes. If one appliance is removed, the others continue to stay on. A parallel circuit also increases the current since there are more ways for the electricity to travel. Our homes are wired in a parallel circuit. If too many appliances are connected into a parallel circuit then he current becomes too high and can heat up the wire. This was one of the main causes for house fires in the past. We installed a fuse box which contains many circuit breakers. A circuit breaker will trip if too much current is present and will break the circuit. This turns off all the power in the house since a box is wired in a series circuit. We use a series circuit in fuse boxes to protect our homes from house fires!

Fuse Box Photo

      This photo is of a fuse box. A fuse box is put in every home as a safety precaution. A fuse box is wired in a series which means if one of the circuit breaker trips, all the power will be cut off. A circuit breaker trips when too much current is present. This high current is caused when many appliances are plugged into the wall. The more appliances are plugged in, the greater the current. This increase in current occurs since most homes are wired in a parallel circuit. A fuse box will immediately shut off all electricity in a house when it detects a high current. This protects our house from electrical fires.