guitar amps and variable resistors

so i was cleaning up my room this weekend and stumbled across my old guitar amp. as i was looking at it i realized that the amp had a lot to do with physics! We had just learned about variable resistors in class this past week and i noticed that the amp has a variable resistor to control the volume. i learned from the equation that resistance depends on resistivity, cross sectional area, and length. As i turn the knob to increase the volume, the length of the conductive material shortens. This results in less resistance, therefore allowing electrons to flow through at a faster rate. as i turn the volume knob down, the length increases, resulting in higher resistance. The electrons to flow slower and the current is decreased which causes a decrease in the sound output.

sound!

so i was in my room listening to some music trying to think of what i should do for my physics journal. and then i realized, hey! there must be some physics in my speakers playing the music. I was very interested to see how it all worked so i went to my trusty text book to learn more about this concept of sound. Sound waves are longitudinal waves that move through a medium like air. I noticed that my speakers vibrate forward and backward. The speakers are actually causing the air or medium to compress and decompress. When the speaker comes forward the air compresses causing the particles to become closer together. This region is of higher pressure and is known as condensation. When the speaker diaphragm pulls back, is creates rarefraction, or an area with fewer particles and lower pressure.

BATTERIES

Today i wanted to watch the super bowl, so i sat down on my couch and grabbed the remote. When i tried to turn on the tv; however, it wouldn't go on. I pushed and pushed, and nothing happened. I was almost ready to give up and not watch it at all, until my sister brought me over a fresh pair of batteries. Batteries are sources of eletric potential energy. The batteries in the remote have a positive and negative terminal (different electric potentials). The voltage of the AA batteries in the remote control is 1.5V. A chemical reaction inside the battery creates electrons. The metal springs in the remote connect the battery's negative and positive ends. The electrons collect on the negative end of the battery, and move towards the positive end. By doing this and completing the circuit, the batteries give the remote control power to change channels.