Monday, May 24, 2010

Electric Circuit Kid's Toy (Snap Circuits)

As I was studying for my Physics final I realized that there was a toy I got from my parents as they have always given me "educational toys."  This one I found showed me how circuits work in an extremely simple format.  Using the snap circuits you can easily construct parallel, complex, and series circuits.  I got this toy, and who knew it could help me so much?  A simple child inspiring toy, applied toward the qualitative understanding of physics.

Here is their link:

Wednesday, May 19, 2010

Connections Through Circuits! Shocking!

SERIES CIRCUIT- In the diagram above we see a series of identical resistors on a wire in a closed loop. The current through the wire is constant, but the voltage is variant upon the resistors in which it travels. The voltage found across both resistors is equal to one half of the voltage across just one resistor because the resistors are identical and the voltage must be provided for both light bulbs. The equivalent resistance we can find in the circuit is equal to the sum of the values of resistance in Ohms added to each other. Therefore we can conclude that the current is constant across the entire wire as there is not a paralell circuit.

PARALELL CIRCUIT- In the image above we see a paralell circuit. In this circuit there are two equivalent resistors that can be treated with an equivalent resistance acting upon the current of the entire wire. The equivalent resistance can be found by adding the inverses of resistances.  Inside the paralell circuit the voltage is constant, but the current varies. We can look at voltage as the capacity to do work.  

COMPLEX CIRCUIT-  In this complex circuit we have a battery, a switch, and then a series of resistors, two in paralell, and one in a series.  The voltage flows from the battery without resistance that sends a current through the wire that feeds the light bulb with electricity.  The voltage across the wire adds up to the voltage provided by the battery, but is variant upon the resistance.  Voltage "pressure" makes the electrons move, and this "pressure" depends on the resistance in which it travels through, similarly to knotting a hose.  The current is constant on the wire outside of the paralell circuit, but inside the paralell circuit the current is reduced because it must feed upon the two light bulbs (resistances) in the paralell.  The paralell circuit has an equivalent resistance, and therefore we can treat it as an individual resistor for total current, and voltage.  The current through each resistor is not then same, but the current sum inside the paralell circuit is the same as the current that goes through the lone resistor on the wire.

A DC (direct current) is the flow of charge that does not vary in direction.  Direct current is used in batteries, solar panels, and when electricity is transported large distances across a wire.  This require a closed loop, a switch, and resistors across the wire.  In a direct circuit there is a direct flow of voltage.

Sunday, May 2, 2010

Optics Reflection

In our most recent unit, geometric optics, I learned quite a lot about how light travels and interacts with mirrors, lenses, and various mediums.  We began our units by learning about waves and sound.  Through this unit we were introduced to the most basic topics that were necessary to understand color, light travel, refraction, diffraction, and reflection.  This unit introduced us to frequency, speed, wavelength, and the Doppler effect. In this unit we also used online wave simulations that demonstrated interference, whether it be constructive, or destructive.  After this briefing, we began to talk about mirrors.  We had various labs where were experimented with flat mirrors, concave (converging) mirrors and convex (diverging) mirrors.  In these experiments we were proved the relation between the focal point and the radius of curvature.  After these qualitative experiments, we were introduced to a style of determining the qualities of images formed by mirrors called the ray-tracing method.  We proceeded to learn about the focal point, radius, center of curvature, real images, virtual images, upright images, and inverted images.  This style of ray tracing has three standard light rays (1, 2, and 3) that go from a fixed position on the reflected object to the mirror in a certain fashion as follows:  ray 1 is drawn parallel to the normal line, and is then reflected off into the focal point; ray two is draw through the focal point, and then reflected off of the mirror parallel to the normal line; ray 3 is drawn from the figure to the center of curvature.  As we draw these ray-tracing models we write down the characteristics of the images formed.  After mastering these concepts we learned the quantitative application to optics.  We discussed and determined how to conclude image characteristics based on our numbers we solved for.  After this we learned about Snell's Law of image refraction.  We then moved on into lenses and talked about the uses of lenses for people with poor vision and how glasses work.  This was particularly fascinating when Cyrus, one of my classmates who is a very fascinated and driven by studies in the brain, gave a presentation from his blog on how the eye works.  We learned about diverging and converging lenses, and learned how to do ray-tracing diagrams for these as well.  We learned that the characteristics of the images lenses produce are very different from how we call the characteristics of images formed by mirrors.  This was a very informative unit full with information and plenty more to study, discover, and explore in the future.

In this unit we covered a lot of material in a very timely manner and I found lenses very difficult.  I thought that I had understood mirrors very well, but when we began studying lenses I was fascinated, but a little bit overwhelmed by the differences.  I found converting quantitative numbers in problems difficult to turn into characteristics and apply them.  

My problem solving skills have become even better in the recent months.  In this unit I was able to draw diagrams that helped me even when they were not asked for.  In my geometry class I have applied this technique of approaching problems and solving them, as I found both this unit and my geometry class very similar.  Especially when I had a hard time answering a question that was more qualitative in more general circumstances, I found that by drawing a diagram I was able to understand the problem more clearly.  This unit not only taught me about optics, but also introduced me to a whole new way of dividing difficult problems into smaller, easier ones.