Variable Resistors in Beauty Products

This past weekend we had a Valentine's Day Banquet at my church to fundraise for a trip we're going on this coming summer. We had to get all dressed up and act like "professional" waitors and waitresses. Thus, before the banquet I turned on my hair straightener to straighten my hair before the dinner so it wouldn't be all frizzy. My mistake came in turning it on the highest heat possible and leaving it on my unmade bed. It burned right through my mattress!! In all this, I realized that my hair straightener has physics to it because it is a variable resistor! When I turned up the heat, I was actually shortening the length of the conductor which is probably located inside of the straightener. By shortening the length of the conductor, I am decreasing the resistance, allowing the electrons to flow easier and have a greater current. A greater current means that there is more power and as a result, more heat coming from the straightener which is why it burned through my mattress!!

Microphones

This past Sunday, my youth group led the worship service at my church. It was a lot of fun because it really brought us together as we prepared for it. Some of us sang, some of us were ushers, some of us signed, and one of the guys in my youth group did the sermon. Anyway, I sang as part of the praise team and (much to my dismay and reluctance) used a microphone. Since I greatly dislike using a microphone, I would always hold it down by my belly button rather than up by my mouth. However, because I did this, the sound people always had to put my microphone on SUPER high and loud in order to pick up my voice. As a result, every time I even came a little bit close to the monitor a loud shrill shreak would sound. I thought that there must be some kind of physics to a microphone in order for it to 1) be able to make that shrill sound and 2) amplify your voice, so I looked up exactly how a microphone works. A microphone gives out an electric signal every time it senses sound pressure variations from your voice. It is made out of a small coil attached to a diaphragm and this coil is free to move inside of a cylindrical magnet. Whenever sound comes into the microphone, the diaphragm vibrates which causes the coil to move up and down between the poles of the magnet and your voice is amplified! I think that the reason why the shrill sound was made every time I came close to the monitor is due to the electric signal that the microphone is constantly giving out. The microphone amplifies every sound that it picks up, including the sound of the monitor. However, the monitor gives off the sound that the mic amplifies. Therefore, there is like a conservation of sound and when you put the mic close to the monitor, they amplify the sounds the other gives off which leads to the shrill shreak. This picture is of one of my best friends Sarah who sang a duet with my youth pastor. She held the microphone correctly (as shown) and sounded awesome!