Thursday, July 19, 2012

Let There Be Light!



Light. A word that we use everyday, but don't entirely understand. We in the physics world use the words refraction, reflection, and dispersion to describe three changes that light can undergo. The picture above contains all three qualities. As the lasers pass through the triangular prism, and the light refracts in order to take the path of least time. Then, this new path of light encounters a concave mirror. The three beams of light reflect off the surface at different angles, meeting at a common point called the focus point. This focus point is indeed a real focus point and not virtual, and the beams actually meet at an actual point. After reflection, the beams go off their separate ways, and undergo what we call dispersion. What were previously solid, seemingly unbroken beams of red light become a spray of scattered, ever diverging light particles that lose their strength over distance.

Tuesday, July 17, 2012

Music


Today, we learned the physics of music! There are three different types of resonant instruments:

1) Strings
Strings are any instruments that create music by the strumming or striking of strings or wires.
i.e. guitars, violins, pianos, etc.
Waves created by strings are not constrained, and generally have long wavelengths. Can be longitudinal or transverse.


2) Open Tube
Open tubes are any instruments that use air being pushed through said tube to create music.
i.e. trumpets, trombones, flutes, miscellaneous brass/woodwind instruments
Waves created by open tubes are constrained and forced through said tube by a flow of air. Can be longitudinal or transverse.


3) Closed Tube
Closed tubes are shut off at one end, and use contact or a flow of air to create music.
i.e. bottles, PVC tubes, etc.
Waves created by open tubes are constrained and always transverse.


Monday, July 16, 2012

Periodical Motion


Today, we studied periodical motion and waves. Periodical is defined as a repetitive occurrence over a given amount of time. One example is ocean tides. Ocean tides fluctuate between high and low tide throughout the day, and surfers and other beach goers can rely on tide charts to tell them exactly when the tides will be high or low. Now that we're on the topic of the ocean, I'd like to talk about waves. No, not the waves you get at the beach, but waves such as sound waves that are not seen, but rather witnessed. Such waves follow a periodical motion, and are called waves because position vs. time graphs of such waves are always shaped like waves that follow a predictable motion.


I learned three new equations:
1. T=1/f, where T stands for period and f stands for frequency.
2. T=2π(l/g)^1/2, where T stands for the period of a pendulum, l stands for length of the pendulum,
and g stands for the strength of Earth's gravity.
3. V=fw, where V stands for velocity, f stands for frequency, and w stands for wavelength.


One real world connection is in jets. Most jets can travel faster than the speed of sound, and when a
jet exceeds the velocity of sound, a visible and audible occurrence appears.


Magnetism


On Thursday and Friday, we studied magnetism. We performed a lab using many scenarios to explore magnetism. We studied how electric currents (moving charges) naturally create magnetic fields, which are in turn very similar to electric fields. We also learned that unlike in many objects, electron spins in magnets all line up, giving magnetic objects two distinctive poles. The only three elements capable of becoming permanent magnets are iron, nickel and cobalt.


I learned one new equation: F=qVB. F stands for magnetic force, q stands for charge, V stands for velocity, and B stands for the strength of the magnetic field.




One real world connection lies in compasses. Compasses use the huge magnetic field of the Earth itself to find in which direction North lies. As of right now, the Earth's geographic north pole is opposite of the magnetic north pole, but compasses take this into account.


Wednesday, July 11, 2012

Lemon Battery


Today in class, we performed a lab using a lemon battery. After rolling and squishing the lemon to get the citric acid flowing freely, we punctured said lemon with a zinc nail and copper penny. The reason we used these two elements is because zinc is fundamentally positive and copper is fundamentally negative. This allows for an exchange of electrons (in other words, electricity). We then used this transfer of electrons to charge a small LED light.


I learned a new equation today: PE=qV. PE (or U) is potential energy of electricity, while q stands for charge and V stands for voltage.


As usual, one real world connection is lightning. Enjoy.


Tuesday, July 10, 2012

Circuits 2.0


Today we learned more about circuits. There are two types of circuits: series circuits and parallel circuits. In a seris circuit, one battery powers multiple resistors and is controlled by one switch. In a parallel circuit, one battery powers multiple resistors again, but each resistor is controlled by its own switch.


I learned that in a parallel circuit, resistance is much greater than in a series circuit. This is due to the fact that less amps flow through each circuit, creating greater resistance. However, both circuits contain the same voltage.


One real world connection lies in sockets. If you put a fork in a socket, the prongs connect with the electricity, and creates a circuit with you on the end of it. Don't try this at home.



Monday, July 9, 2012

Circuits


Today, we studied circuits. Circuits are a continuous line of conductors that loop together to provide a pathway for electricity to flow through. Circuits require an energy source, and many have components that either: a) control the flow of energy (a switch) or b) consume the energy (a lightbulb).

I learned two new equations:
  1. V=IR, where V is voltage, I is current, and R is resistance (ohm's law).
  2. P=IV, where P is power, I is current, and R is resistance.

One real world connection is in our houses. Every little electronic appliance we take for granted runs through a circuit board that controls all power in our homes. When we use too much energy, it's the circuit boards that save our homes from fire.