Right Hand Rule#1&2

Right-Hand Rule #1 (RHR #1)
Right-Hand Rule #1 determines the directions of magnetic force, conventional current and the magnetic field.  Given any two of theses, the third can be found.
 

Using your right-hand: point your index finger in the direction of the charge's velocity, v, (recall conventional current). Point your middle finger in the direction of the magnetic field, B. Your thumb now points in the direction of the magnetic force, Fmagnetic.

Right-Hand Rule #2 (RHR #2)
Right-Hand Rule #2 determines the direction of the magnetic field around a current-carrying wire and vice-versa

Using your right-hand:

Curl your fingers into a half-circle around the wire, they point in the direction of the magnetic field, B
Point your thumb in the direction of the conventional current.

Ten Points For Magnetism

1. Magnetic field--the distribution  of a magnetic force in a region of a magnet.
2. similar magnetic poles, north and north or south and south, repel one another with a force at a distance. Dissimilar poles, north and south, attract one another with a force at a distance.

3. Domain Theory all large magnets are made up of many smaller and rotatable magnets, called dipoles, which can interact with other dipoles close by. If dipoles line up, then a small magnetic domain is produced.
4. Oersted's Principle Charge moving through a conductor produces a circular magnetic field around the conductor.

5. Right-hand rule #1(RHR#1) for conventional current flow Grasp the conductor with the thumb of the right hand pointing in the direction of conventional, or positive(+), current flow. The curved fingers point in the direction of the magnetic field around the conductor.

6. Left-hand rule #1 for conductors Grasp the conductor with your left hand such that the thumb points in the direction of electron(-) current flow. The curved fingers point in the direction of the circular magnetic field around the conductor.
7. Right-hand rule #2(RHR#2) for conventional current flow Grasp the coiled conductor with the right hand such that curved fingers point in the direction of conventional, or positive(+), current flow. The thumb points in the direction of the magnetic field within the coil. Outside the coil, the thumb represents the north(N) end of the electromagnet produced by the coil.
8. Left-hand rule #2 for coiled conductors Grasp the coiled conductor with the left hand such that the curled fingers point in the direction of the electron（-）current flow through the conductor. The thumb points in the direction of the magnetic field within the coil. Outside the coil, the thumb represents the north(N) end of the electromagnet produced by the coil.
9. The magnetic field strength, B, is measured in units called tesla (T).1T is the magnetic field strength when a 1m long conductor, carrying a current of 1A, crosses a magnetic field at 90°, experiencing a magnetic force of 1N.
  the equation is 1T = 1N/A·m
10. Iron, nickel, and cobalt are ferromagnetic metals.

10 Points From Pg553-563

current flow is dependent on the voltage of the power supply and the 'nature of the pathway through the loads that are using electric potential energy'

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

Electrical resistance is the measure of an opposition in the flow.

series circuits connect loads in a single path

parallel circuits connect them parallel to each other.

Kirchhoff's current law: the total amount of current that flows through a junction point is the same as the amount of current that flows out of that same junction .

Kirchhoff's voltage law: the total amount of potential decrease in a circuit loop is equal to the total amount of potential increase in that same loop .

the resistance of a conductor depends on its length, cross-sectional area, the material it is made of, and its temperature.

Thinner wire has a larger resistance than thicker wire.

The gauge number of a wire indicates its cross-sectional area. In other words, a small cross-section has a large gauge number.

Just A Table......

Prelab: Using Voltmeter and Ammeter

Done......

energy ball and the diff between a series and a parallel circuit

On friday at Mr. Chung's class, we played the whole period with a ....ping pong ball= =!

Obviously it's not the one we're usually play with(the one is shown above...), it's actually a ping pong ball with electric circuit inside it, and there were two piecies of metal on the surface of tha ball, when your fingers touch both sides of the metal, the ball will start flashing and humming, so we call it "energy ball"! we were divided into groups of 4, and each group was given a envolop with 12 questions inside.

Q1. Can you make the energy ball work? what do you think makes the ball work?

      Yes, of course- -! The ball is actually an opened circuit, the two piecies of metals is actually act as the opened switch. When our fingers touch both sides of the metals, we actually connect the circuit with our body. So the whole electric circuit is complete and that makes the ball work.

Q2. Why do you have to touch both metal contacts to make the ball work?

      I just answered this question at Q1...we have to touch both metal contacts because we have to complete the circuit. Again the ball is an opened circuit, and us were acting like a conducter, when our fingers touch both metals, we actually make the circuit inside the ball.

Q3. Will the ball light up if you connect the contacts with any material?

      The ball can light up as long as the material is a conductor or some materials sort of metals.

Q4. Which materials will make the energy ball work? Test your hypothesis...

      Any materials as long as it is a good conductor..

Q5. This ball does not work on certain individual - what could cause this to happen?

This ball does not work when the material isn't a good conductor.

Q6. Can you make the energy ball work with all 5-6 individuals in your group? will it work with the entire class?

     Yes, of course//the enery ball lights up in my group by connecting hands. It will surely work with the entire class as long as everyone connects their hands with each other. 

Q7. What kind of a circuit can you form with one energy ball?

    My group formed a DC, which is direct current. because as the definition for DC is: the current flows in a single direction from the power supply to through the conductor to a load. We are actually making a circuit and the electric just moved through our body. It fits the definition for a DC.

Q8. Given 2 balls(combine two groups) can you create a circuit where both balls light up?

Yes! We joined another group and hold our pinkies together to make a circle(you always have to make a circle), just as what we did for the first one, the only difference is this time, we need two people to hold the balls. And it surely works~ we made both balls light up.  

Q9. What do you think will happen if one person lets go of the other person's hand and why?

When one person lets go of the other person's hand, that means the circuit is incomplete, since the circuit is incomplete, the ball won't light up. Because inside the ball, it is a DC current, when the current is disconnected, the electric ccannot transfer, so that the circuit won't be completed, and the ball won't be light up.

Q10. Does it matter who lets go? try it...

No, it does not matter. No mater who lets go, that means the ciecuit would be disconnected. Which indicates the electrons cannot pass on, and obviously the ball won't light up.

Q11. Can you create a circuit where only one ball lights(both balls must be included)

YES! In parallel circuit the above situation appears. As the picture shown below, in parallel circuit, even if one circuit is disconnected, there's still another circuit will be connected, in this situation, there's only one ball lights up, but there're really two light bulbs present.

Q12. What is the minimum number of people required to complete this?

 The minimum number of people that are required to complete this parallel circuit is 5.

                                                                                                                                                   
THE  DIFFERENCE BETWEEN A SERIES AND A PARALLEL CIRCUIT

The difference is that a parallel circuit has more than one path in the circuit,

and a series circuit only has one way around it.

【Blog#2】tall structures

Yesterday I built up a tall structure with Jess and Linda. First we thought that to make a stable structure, the base should be a close-to-triangle structure. So we rolled the newspaper and fold it to make a triangle structure as the base. Then we tightly rolled the rest of the newspaper (so the roll would be longer and taller) as the body of the tower. at first the structure cannot balance itself, but we don't want to kill the height of it, after our little discussion, we found out that the tower cannot stand because the top part was so heavy, so we decided to flip it over, we flipped the top of the newspaper to the bottom and taped it on the base so it stayed stable.




Now the question asks for the physics of tall structures, according to my experience, I'll say that the physics I tested out from the challenge is the mass of weight. As I said before, if the top part is heavier than the bottom part, the structure wouldn't be balanced. The less weight at the top, the more balance the structure will be. Another words, the base is important, the top is also important. We all know that the base should be heavier and bigger, such as the structure of a tumbler. But we often ignored the top part which is also an important part of the entire structure. as a result, the mass of weight is one of the physics of tall structures. For the second question: what makes a tall structure. I think this question is a bit similar as the first one. As I mentioned before, the more weight at the bottom, the more balance the structure will be. So for the purpose of making a balance tall structure, the first thing we'll need is a heavy and big base. And again, the body part should be light to make the whole structure stable. To sum up, the heavy base and the light body make a tall structure.



The centre of gravity is a geometric property of any object. In other words, the center of gravity is the average location of the weight of an object. For different shapes of objects, the centre of gravity is also different.

【Blog#1】Notes on Current Electricity

1. the definition for current is the rate of charge flow. it is a flow of negatively charged electrons repelling one another. and the equation for current is I = Q/t .

2. example#1:

    example#2:

3. the definition for conventional current is the model of positive charge flow.

4. current is flowing from the black negative(—) terminal to the red positive (+) terminal.

5.the electric potential difference is the difference in electric potential (V) between the final and the initial location when work is done upon a charge to change its potential energy. in equation form:V = E/Q. potential difference is often called voltage and the unit for this is the volt.

6.electric circuit is simply a closed loop through which charges can continuously move.for an electric circuit, the energy delivered to the load depends on the potential(energy per charge) and the rate at which the charge is delivered( the current). the energy transferred by charge flow is E = VIt.

7.how to draw circuit symbols? see textbook P547 for more info.

8.a direct current(DC), the current flows in a single direction from the power supply through the conductor to the load.(eg:light bulb)

9.a alternating current(AC), the electrons periodically reverse the direction of their flow. 

10.images of electric circuits.