Motors

For the past couple days in physics we have been learning about and making motors.

There are two necessary components of a motor, a current carrying wire and a magnet.

The current carrying wire feels a force from the  magnetic field, creating a torque.

The motors we made consisted of a wire coil, a battery, a rubber band, a magnet and a couple paper clips.

The motor looked something like this

An example of when a motor is used is in a car. A motor is what causes your wheels to rotate. 

Here is a video of my little motor in action.

Unit Summary # 6

During this unit we talked about six major topics:

1. Charges and Polarization(Coulomb's Law)
2. Electric Fields
3. Electric Potential/Electric Potential Difference
4. Current/Types of Current
5. Types of Circuits 
6. Ohm's Law  

Charges/Current/Coulomb's Law

 Objects have protons and electrons. When they have more protons than electrons or electrons than protons, they become positively or negatively charged, respectively. 

Things that have like charges repel each other while things with opposite charges are attracted to each other.

How do these charges travel and move? There are 3 ways:

1. Direct contact (shocked someone by touching them)
2. Friction (furry puppy below)
3. Induction charge without contact (lightning)

This dogs fur becomes charged through friction

Polarization

When an object is polarized, it is not charged, the charges are 

simply rearranged.

Here is an example:

The charged balloon comes in contact with the wall and the wall is

 polarized. 

This happens because of the like charges repelling each other. We 

can see this interaction in the formula for Coulomb's Law which 

states:

F= (k q1 q2)/d ²

where q stands for charge

The closer the like charges get, the more the charges repel. If the

 charges are opposite, the charges will attract with that same force,

 which is why the ballon sticks to the wall. 

Electric Fields

Electric fields are the area around the charge that can influence 

(push or pull) another charge.

How do we draw electric fields?

·       If a positive charge were close to the positive charge on the left, it would repel away

·     If a positive charge were close to the negative charge on the right, it would be attracted inward.
And notice how as you travel further from the charge, the lines get farther apart. This indicates the strength of the push/pull decreasing.

Current

Current is the flow of charge

Charge flows when there is a difference of potential energy between two points, and it will continue as long as there is electric difference between these two points.

It is important to remember that voltage causes current, current does not cause voltage

There are two kinds of current, AC and DC:

• AC - Alternating Current  
• switches direction
• used in batteries
• DC - Direct Current
• used in wall sockets

Circuits

Circuits are what allow the flow of the current. There are two kinds of circuits that we have learned about this year, series and parallel.

In a series, if you have multiple appliances, they are all part of one circuit. If one of the appliances goes out, the current stops flowing because the circuit is incomplete. Also, the current supplied is divided among the appliances. For example, if there were two light bulbs, they would both be dimmer than if there were just one light bulb.

In a parallel circuit, each appliance has its own circuit attached to the power source. If one appliance goes out, the rest keep working. This is the kind of circuitry you have in your house. However, parallel circuits can be dangerous because there can be a lot of current flowing through the wires which can cause them to over heat. This is why we have fuses. If there is too much current, the fuse will break, protecting your home.

Ohm's Law

All of this leads into Ohm's Law which states:

I=V/R

This means that the current equals voltage over resistance. More voltage, more current. More resistance, less current.