Building an Electric Motor

  For -Building an Electric Motor-this project, our task was building an electric motor and make the motor spin, when it connects the power supply. Firstly, we hammered the four nails in to the wood, the distance between was 5cm×3cm. Secondly, we made the Axel went though the cork, there are two pins place into the centre of the each end of the cork, we sanded the end of two side of the wire and we wrapped the wire around one of the commutator pins and around the cork, other end of the wire it wrapped around the other commutator pin. Thirdly, we used the pop can for the brush but before we use it we had to sand it all over perfectly and used the thumbtack to make it staple. In addition, we used two paper clip bearings to hold up the axel, and make sure it could spin. Lastly, we put 2 magnets, one on each side, and connect the power supply made the motor spin.

Right Hand Rule #1 and 2

Right Hand Rule #1:

Current flow from positive to negative, the thumb of the right hand is pointing to the positive current flow and the curved fingers are pointing to the direction of the magnetic field around the conductor

It is the positive direction of the current flow

It is the negative direction of the current flow

Right Hand Rule #2 rules for coils:

In right Hand Rule #2 the Current flow from positive to negative.

Curved fingers around conductor, the curved fingers point the direction of positive current flow, and they represent the current. The thumb points the direction of the magnetic field and it represents the direction of the north.

The Magnetic Force P582~589

1. Magnetic field is the distribution of a magnetic force in the region of a magnet
2. There are two different magnetic characteristics: north and south are responsible for magnetic force
3. Similar magnetic poles they repel one another, dissimilar poles they attract one another

4. Iron, nickel, and cobalt are ferromagnetic metals

5. All magnets are made from Iron, nickel, and cobalt

6. Magnetic material as composed of many small magnets and is called to domain theory of magnets

7. Domain Theory all large magnets are made up of small and rotatable magnets, called dipoles, therefore they can interact with other dipoles close to each other.

8. If dipoles lines up, a small magnetic domain will be produced

9. Oersted’s Principle: a circular magnetic field around the conductor produces when charge moving through a conductor

10. There are three Right hand rules, which involve using our hand, they abbreviated as RHR.
11. RHR #1 conventional current flow, straight thumb along conductor.

12. RHR #2 right hand rule for coils, curved fingers around conductor

10 POINTS FROM P553~563

1. (1) the potential difference of the power supplies (2) the nature of the pathway through the loads are the two things of the amount of current flow in a circuit and the energy transferred to useful device.

2. Two of the simple circuit, the first circuit allows the circuit to pass though the load easier than the second circuit, in the two circuits, their potential difference is the same, but the pathways are different.

3. The more difficult the pass, means the more opposition there is to flow. Electrical resistance is the measure of this opposition to flow.

4. R is the resistance in volts/ampere, Ohm（Ω）is the unit of the resistance.

5. V/I this ratio is called Ohm’s law

6. The resistance of a conductor depends on 4 major things: its length, cross-sectional area, material, and its temperature.

7. Series circuit and parallel circuit are the two simplest ways to connect conductor and loads.

8. In a series circuit the loads are connected one after another in a single path

9. In a parallel circuit the loads are connected side by side

10. Kirchhoff’s current law: the total amount of current goes into a junction point equals the same amount of current that flows out of that same junction.

                                           

11. Kirchhoff’s voltage law: the total amount of potential decreases in any complete circuit loop is the same number as the electrical potential increases in that circuit loop

12 . Vt = V1+V2+V3 so, there is no gain or loss of electric charge or energy in a circuit.

The Chart of Prelab

Question 1-12 & the different between a parallel and series circuit

1.Can you make the energy ball work? What do you think makes the ball flash and hum?
Yes, I can make the energy ball work, because we complete the circuit, and we are the conductor

2.Why do you have to touch both metal contacts to make the ball work?
We have to touch both metal contacts to make the ball work because we complete the circuit

3.Will the ball light up if you connect the contacts with any material?
The ball only light up with metals, conductors and water

4.Which materials will make the energy ball work?
Metals and water can make the energy ball work

5.This ball does not work on certain individual, what could cause this to happen?
This ball does not work on certain individual skin; where the skin is dry and don’t have any moisture, the ball will only work on the moisture skin.

6.Can you make the energy ball work with 5-6 individuals in your group? Will it work with the entire class?
Yes, it is a complete circuit

7.What kind of a circuit can you form with one energy ball?
Simple circuit

8.Given two balls, can you create a circuit where both balls light up?
Yes, simple circuit

9.What do you think will happen is one person lets go of the other person's hand and why?
The ball will not be light up, because there is no complete circuit.

10.Does it matter who let's go?
No, it does not matter

11.Can you create a circuit where only one ball lights (both balls must be included in the circuit)？
Series and Parallel circuit

12.What is the minimum number of people required to complete this?

5 people is the minimum number of the people required to complete this

What is the different between a parallel and series circuit?
In a series circuit the loads are connected one after another in a single path

In a parallel circuit loads are connected  are side by side

Challenge of the Structure

1.The physics of tall structure

A tall structure needs to have a big and stable base that can support the whole weight of the structure, and the weight become lighter and lighter as the higher they go.


2.What makes a tall structure stable?

First, the weight of the base must heavier than the weight of the top. Second, the base needs to be big and in a stable shape, for example triangle, it is the most stable shape, so it is not easily to broken down. Third, the structure has to be symmetry. Finally, the top of the structure has to be perpendicular to the ground. Center of gravity of the structure is the same place of the center point of the base.


3.What is the centre of gravity?

The center of mass is the point where the gravity is considered to be acting the most within the object

Notes on Current Electricity

1. Static state electrons have energy, electrons become more useful when they are made to transfer their energy

2. In an electric circuit, energy source always provides electrons with energy

3. The electrons are transport by conductors, to where the electrons energy is transferred, then back to the source be re-energized.

4. The flow chart is called electric current

5.Current is the rate of charge flow

6.Current is the total amount of charge moving past a point in a conductor divided by the time

7.Current flow move form positive terminal to negative terminal of any power supply

8.A coloured wiring use black represents the negative terminal and red represents the positive terminal

9.Direct current, the current flows in a single direction from the power supply through the conductor to a load and back to the power supply

10.Electric current to flow: it must have a complete path from the negative side of the power supper to the positive side

11.The path of current is called current

12.Excess of any one charge will cause a force of repulsion

13.The electrical potential energy for each coulomb of charge in a circuit is called the electric potential difference [V] it is often called voltage

14.Using a voltmeter to measure potential difference between any two points