Unit Summary

Blog post summary—Electricity

Electricity is made of charges some positive and others negative. Like charges repel each other while opposite charges attract each other. When they are stationary in the object the object is neutral or has no charge greater than the other. When an object becomes charged the opposite charges are pushed away and out of the object, through friction, touch, or induction and the object has an unbalanced amount of charges. The object is now polarized and attracts the opposite charges in other objects.

Induction is the transfer of charges through the air without the objects touching each other. This is how lightning works. The charges build up in the cloud through friction and the positive charges are pushed to the top of the cloud. The negative charges at the bottom of the cloud are attracted to the positive charges on the tops of buildings and the ground. When enough energy is built up the positive charges move towards the negative charges and the connecting of the opposite charges creates the light known as lightning.

Each charge has an electric field, an area that influences other charges based on the properties of the charge emitting the electric field. The electric fields are marked by arrows pointing the way that a positive charge would be moved within the electric field. So a positive charge has arrows pointing away because the positive charges would be pushed away if they came too close whereas a negative would be pulled closer. The distance is very important. Coulombs’ Law (F=kq1q2/d^2) states that the distance is squared and inversely proportional to the force between the charges.

Electric shielding works because of Coulombs’ Law makes the distance influence the amount of force. The force that a charge puts on the charge inside the shield depends on where the charge is inside. If it is closer to one side then those charges that are near it have more force on the charge, but the other charges still have a force on that charge they are weaker because of the distance. There are so many charges with weak forces that they balance out the charges with the stronger force thus keeping the charge in the inside neutral.

Volts are the amount of electric potential in an object and voltage is the difference in volts between two areas. Only when there is voltage is the energy flow through making the current move in the circuit. A circuit is when the area of different voltages is connected through something that allows the energy to flow through it. The energy that flows through it is called the current.

Circuits can be wired in different ways, parallel, series, and with fuses. The parallel allows multiple access points to the energy to be drawn at the same time while the series requires access points to be stacked on each other in order to add more appliances. Fuses are used for safety so that if too much current flows through the fuse breaks and the flow is stopped thus stopping any risks of damages. The parallel draws more current each time another appliance is plugged in while the series reduces the current flow.

The reason that the series is safer is because of resistance. In Ohms’ Law (I=V/R) it states that the resistance is inversely proportional to the current while the voltage is directly proportional. Each appliance that is plugged in adds some resistance to the circuit and in series this does not matter because it only makes the circuit safer. But in parallel it makes no difference because the more appliances are added the more current it draws despite the resistance. This is caused by each appliance in a parallel circuit to being wired separately and drawing more and more current.