Sinusoidal Waves

It was a pleasant day today here at Penn.  In class, we had had guest speaker and watched a video about a professor from Penn about his astronomy research.  Our guest speaker was Dr. Alison Sweeney, a Biophysicist who studies different types of squid in the ocean and uses physics to describe their different physical properties.  It was an interesting approach to Biology that demonstrated how physics can be used to describe everything in the universe.  I think that is the reason why I appreciate physics so much, because it is the study of the most fundamental principles of all matter and behavior, despite the fact that it only appears to be a real life demonstration of mathematics. 

Today we also found out that from now on we will only be performing one lab a day instead of two.  I personally like this process because it allows for more time to explain the material before heading to the lab.  Speaking of labs, today’s lab was a very interesting one.  We were measuring the electrical currents generated by sound waves and then an electric pulse devise in order to calculate the speed of sound and electricity.  We were using a machine called a digital oscilloscope to graph the different electrical waves on a screen.  The way it works is that you can use a speaker as a microphone to transmit an electrical signal to the oscilloscope.  When a sound wave bounces off of the sub-woofer  the sub-woofer gets pushed down onto a coil of copper wire which is connected to a magnet inside the speaker.  The combination of movement from all the moving parts creates the electric signal which is sent to the computer.   I found this lab to be fascinating in every way.  I didn't expect that we would be using such sophisticated and expensive equipment.  The oscilloscope basically looks like a heart monitor, a very expensive heart monitor and it was a dream come true to be able to use it.

After the official lab was over and almost everyone had left, a small group of us stayed to fiddle with the machines.  We decided to use a resonance generator in order to see what the different types of sound waves look like.  The resonance generator is basically a speaker that can generate different frequencies of sound ranging all the way from one hertz to beyond the realm of human hearing.   We discovered what speeds the different waves travel at and the features of their graphs.  During this time, Bill Burner took the time to elaborate on the different sounds that we were testing and also gave us some helpful insight on how to use the machine, giving us a distinct advantage over the rest of the class for tomorrows lab.