July 19, 2012 Light & Optics Test

 
Standard 10.1: Through this convex lens, the image behind it can be magnified to a certain extent depending on its distance from the object. Although this image does not create a rainbow, however, it does represent the relationship between frequency and color. For instance, the ceiling in the background is of a white color. Therefore, the ceiling basically reflects all other colors that come into contact with it. Also, My skin absorbs the certain light of color which gives it its certain pigment. In addition, my black hair is the color it is because it absorbs all light. This is why when someone wears black on a hot day, he feels very warm.

Standard 10.2: The index of refraction of this convex lens is 1.52. Compared to the index of refraciton of the air (1), the light will move at a slightly slower rate. As a result, the light will travel closer to the normal line. Using Snell's Law, we can determine that the light travels into a different medium as it goes from the air, through the convex lens, and then back out the other side of the lens. This explains why the lens has the property of magnification.

Standard 10.3: This convex lens has a different medium than that of the air. This causes the property we know as magnification. The light going into the lens does not reflect off the lens, rather it refracts through it and causes the image on the other side to appear larger. This "real image" occurs due to the light rays in space that focus together in space with the image and the observer  (the camera) on the same side.

July 17, 2012

Today we began with a new discussion on the concept of sound, and more importantly resonance,

Resonance: When one object vibrating at the same natural frequency as a second object forces that object into motion.


1. antinodes - areas of complete constructive interference
2. nodes - areas of complete destructive interference
3. harmonics - # of humps Next, we went onto our lab in which we measured the frequencies of our PVC pipes and then figured out which specific notes they corresponded to.

In addition, we also had a little fun with our new instruments by playing songs with them!
http://vimeo.com/45922358
 ^^^^

RWC:
For those who play the xylophone, they should know that the secret behind playing this fun instrument is that each note produced by hitting the scale is just a different frequency. And that all of the frequencies together produce beautiful music.
 

July 16, 2012

Today we started off class with a discussion of our new lessons on simple harmonic motion:

Periodic Motion: repeats itself in a pattern

-frequency[squiggly f] measured in hertz[Hz] = #cycles/seconds
-Period[T] = #seconds/1 cycle

New equations:
f = 1/T
T[pendulum] 2(pi)[sq root of l/g]

Graphs for periodic motion are always sine waves

V = Wf
Velocity = wavelength x frequency
Next, we went onto our labin which we experimented with the cycles and periods of pendulums, and experimented with the frequency of water.

Waves:
A wave is a transfer of energy
Two types of waves:
Transverse wave: medium oscillates up and down, wave moves perpendicular
Longitudinal wave: medium + wave move in same direction

Constructive interference: where two waves collide and form 1 giant wave
Destructive interference: where two waves collide and cancel each other out.

RWC:
Whenever you're down at the beach watching the waves, you can often see both constructive and destructive interference occur where waves collide and form different shapes and sizes

July 12, 2012

We started off the day with our Post Game Analysis:
1. Electric current creates a magnetic field that can generate a magnetic force. (i.e. doorbell, solenoid +compass, wire)
2. If you move a magnet in the presence of a wire, electric current will start to flow. (Hand crank generators, online phets) Next, we performed our motor and speaker lab in which we built a prototype motor and speaker from a magnet, wire, paperclips, a block of wood, and a battery.

After that, we went onto take our electromagnetism test.

RWC:
In order to start a leafblower, you must pull on the cord to start the engine. This causes the magnetic fields within the leafblower to begin repelling and attracting each other. This is how many machines nowaadays function.

July 11, 2012

Today we performed the lemon battery lab in which we created voltages that increased with the amount of lemons we used.

Next, we continued on with our study of electricity by learning two new equations about electric potential energy, and electric potential.
Electric potential = voltage (V).
Electric potential energy:
U[e] = qv
    Afterwards, we went onto take our circuits test.

RWC:
At your typical science fair nowadays, you'll most likely see someone with a potato battery powering a lightbulb or a clock. This uses the exact same concepts that our lemon batteries used in which one source of positively charged particles reacts with another side of negatively charged particles to create the energy needed to power a small device such as a clock or calculator.

July 10, 2012

Today began with our postgame analysis:
1. Ohm's law: V=IR
2. Circuit is called a circuit because (circle) it is a closed loop in which charges can flow through
3. Resistance = 1V/1A

















Next we moved onto our lab in which we built parallel and series circuits by ourselves.


 Rules:
1. Everywhere along a wire has the same voltage
2. Voltage does not occur only across resistors.
Positive current flows from high V to low V
3. Current is conserved (total charge in = total charge out)
 
Analysis:
Series circuit: The total resistance = the sum of all resistances. Also, the current remains the same while the voltage drop differs
Parallel circuit: The total resistance = The sum of both halves (or more) of the circuit. The current is different in different areas while the voltage drop is the same.

Real World Connection:

Depending on its use, any house or electronic device could be built with different circuitry to fit the user's various energy needs whether he prefers a higher voltage or better resistance.

July 9, 2012

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We started off today by taking our electricity test.

 Then, we performed the circuits lab in which we both digitally and physically created our own working circuits. We made light!

Afterward, we hada discussion on the concepts behind circuits and power:
Power - rate of energy consumption
Power = energy/time
Voltage = current x resistance
Energy consumed = Power x time (J=watts x seconds)
Power = IV

Real World connection:
In most houses circuit breakers are installed to keep the energy levels from becoming dangerously high. When the level of electricity in a certain area reaches a certain limit, they shut down all power.

July 5, 2012

Today was a really productive day for the whole class.
We started off the day by discussing charges - what they are, how they look, and how they are transferred
A charge is the force of electromagnetic interaction within an object
Charges are seen or felt as shocks, light, attractions and repellents
They are transferred through the movement of electrons, separation, and through the power of friction.

Next, we had our Electrostatics investigation lab where we tested the properties of electricity, especially static eletricity by charging certain objects and determining whether they repelled or attracted a negatively charged balloon.

Afterwards, we learned about conduction and polarization:
conduction is the ability to, in this case, transfer electricity
Polarization is just a fancy word that scientists use for the separation of charges within a substance

Lastly, we learned two new equations dealing with the properties of electricity:
q = eN
in other words... charge = 1.6x10^-19 times the number of electrons.

E = kq/r^2
Real world connection:
On a hot day at the playground, riding down the hot plastic slide can cause you to feel a bit of a shock. That is because plastic is an excellent conductor of electricity and the friction caused by your sliding down on the slide will create a transfer of the electrons in the slide.

July 3, 2012

Today, I started off class with a new outlook on Newton's 3rd Law by learning about the physics behind throwing a curveball in baseball. Due to the spin put on the top of the ball, there is an equal and opposite reaction with the air on the bottom of the ball. This gives it the "curve" that always confuddles hitters.

Big Ideas:
1. A force is not required to keep an object in motion...ONLY to accelerate!

2. Horizontal forces (F[x]) + motion (V[x]) are independent from vertical forces (F[y]) & motion (V[y]).

Next, we learned that a projectile is
-An object by which the force of gravity is the only force acting on it
-It also travels within the path of a parabola
-This is due to the force of gravity acting down on it.
-Acc. due to the force of gravity on Earth = -10m/s^2
-x-axis is always constant

 
Real World Connection:
During the track and field Olympics this year, those in the event of the shot put must fire a spherical weight at the farthest distance possible. They will find that because of physics, no matter how hard they throw, the object will always fall down fairly quickly. This happens because gravity is continuously accelerating the projectiles at -10m/s^2.

July 2, 2012

Today, our main idea in class was to determine that in order to find the magnitude and direction of a diagonal line on a free body diagram.

In order to find the net force on such a diagram, we must divide the diagonal vector into two vectors of their own, and then calculate normally from there. We do this by using the rules of sine, cosine, and tangent.

We applied these same ideas in our hover cart lab in which we attatched a rope to our hover carts and moved them around to exemplify our new understanding of vectors.
 

In addition, we learned that in a free body diagram, when the force and velocity are the same, the object is speeding up, but when they are different, the object is slowing down. Real world connection: When someone walks a dog on a leash, he controls the dog by changing the vector by which he holds the leash. This concept applies the information that we used in the lab today with the hover carts. Also, it would be possible for the owner to measure the diagonal vector by which he holds the leash.