Polarized Sunglasses

I just so happened to be looking out one of the windows in my house and noticed the brightness of the sun on the hibiscus tree in my yard. The sun contains light waves that travel in different directions in many planes and reflect off objects to create glares. Since we just covered polarization in physics, I thought it would be a good idea to take a picture of the effect polarized sunglasses have on blocking some of the light waves from the sun.

Polarized sunglasses reduce the amount of light passing through by only admitting certain light waves that move in a certain plane. After trying on my sister's polarized sunglasses, the hibiscus tree didn't appear to be as bright as before. The unpolarized sunlight becomes polarized as certain light waves are blocked by the sunglasses. The polarized light oscillates in a single plane unlike its random movements in many planes when it was unpolarized.

Some examples of unpolarized light are the sun and incandescent light bulbs. When these lights are filtered, only certain light waves are admitted and become polarized.

Orchestra Concert!

Yesterday Orchestra 4 and 5 had a concert at Mamiya Theater. I couldn't believe this was the last concert I was going to play in as a member of Orchestra 4. It was kind of sad to know that I won't be involved in orchestra anymore after the end of the school year. By the end of the last piece we played, it sort of hit me that my time in orchestra for the last four years is about to come to an end. I decided to do this week's journal on material we covered last chapter about frequency.

Physics is clearly in play during an orchestra concert. Each instrument, whether string or wind, expresses certain frequencies to produce sound. The fundamental frequency of a string instrument like a violin is determined by the the string's mass per length and tension. Both change the wave speed of the string which change the frequency of the strings. Each string on the violin has a different linear density and tension. Tension on the string can either increase or decrease by turning the tuning pegs by the scroll of the violin. Playing certain notes on the violin create specific lengths that therefore create different fundamental frequencies. The fundamental frequency is calculated by dividing the wave speed of the string by two times the string length or the string's wavelength. Harmonics are multiples of the the fundamental frequency.

Music created by instruments is all because of physics!

Sound Waves

Last week I borrowed a couple cds from the library to listen to. I was excited to have borrowed two of Coldplay's albums. After compiling the songs I liked out of the stack of cds, I downloaded them to my mp3 player. In physics, we are currently learning about waves and vibrations. I am able to listen to the cds on my stero because of the sound waves that protrud from the stero. Vibrations within the stero create sound waves that carry energy and are interpreted into sound by my ears. Vibrations are any periodic motions that move back and forth. Any kind of waves, such as sound waves, are made of vibrations that move through any medium and are classified by how particles move. Sound waves are known as longitudual waves, meaning that particles in the medium vibrate parallel to the direction the wave is traveling. As sound waves travel, they spread out and the intensity of the soud diminishes with distance.

When I turn up the volume to the stero, I change the amplitude of the sound wave by making it higher.

I didn't pay attention to how physics played a role in how my stero works until learning about this chapter. It is pretty interesting!

Posing with Home Meter!

Here I am posing with my home meter! Thanks Mr. Kohara for the extra-credit!

Magnets

We recently started on a new chapter in physics dealing with magnets. We've learned what a magnet is made up of and the physics behind its properties. I wanted to take a picture of a magnet attached to my refrigerator because it best shows the reason why magnets are able to stick to certain household items.

A magnet is an object that creates a magnetic field and exerts a magnetic force. The magnetic field formed in magnets is due to ferromagnetism. In ferromagnetism, the magnetic dipoles of atoms within a material align in the same direction, this is called exchange coupling. Due to an external magnetic field, the dipoles stay aligned and a magnet is created.

Domains or dipoles can easily be disaligned if the ferromagnetic material is exposed to heat or dropped on the ground.

Carnival Fun!

Last weekend, I went to the Punahou Carnival with my sister. I can't believe so many people can be at one place at one time. There were a swarm of people. I constantly had to squeeze between them just to get through. The main reason we went to the carnival was to check out the white elephant. You can find a lot of good stuff at cheap deals. Unlike last year, they didn't have bags to stuff whatever you want in it for a certain price like $5. Bummers....but we still got good stuff! Anyways, besides going to the white elephant, we walked around and went to the game booth. A lot of the games had signs with flashing lights. Those flashy lights reminded me of physics. Particularly circuits.

Light bulbs light up because they are connected to a circuit. All circuits have a voltage difference in which electrons flow from high voltage to low voltage and a closed pathway. In the case of the flashing light bulbs, electrons from a voltage source flow into the light bub causing it to light up then leave the bulb. The higher the voltage within a bulb, the brighter it is. Less resistance could also make the bulb light brighter. When the current within the circuit moves faster, more work is being done in the same amount of time, producing power.

Voltage

Batteries are essential to our lives because we use them to power our appliances. The batteries power can be explained through the concept of voltage, which is what we are currently looking at in electrostatics.

Chemical energy within the battery allows it to operate and separate the negative and positive charges. In order to separate the charges, the battery must do work on the charges. This work is called voltage.

Voltage is a ratio of potential energy per charge or work per unit charge. The SI units for voltage is volts. One volt is equal to one joule/coulomb.

I can't imagine what I would do without batteries. Now that I think about it, batteries really have a lot to do with physics, especially with electric potential energy and what goes on within the battery to produce power. Thank goodness for batteries!