Index+of+Refraction+2

The idea of the index of refraction followed me wherever I went, the idea that the velocity of light changes depending on its medium.

The professor discussed that light takes the path that takes the shortest time to travel through. When light approaches mediums that either slow down the speed of light or increase the speed of light, light refracts to take the shortest traveling distance.

The professor had a great demonstration. He placed Barbie in the middle of carpet ocean and placed Ken on a carpet beach. He then added a shark to the mix by placing it in the ocean near Barbie. The professor posed the question, "What path should Ken take knowing that he can run faster than he can swim if he wants to save Barbie from the shark?" Of course, swimming is the shortest path, but on the other hand, if he can run faster than he can swim, it would not be unreasonable for Ken to run until he gets to the distance from Barbie that requires the least amount of swimming. The professor resolved that Ken would take a path in between these two paths. He made the comparison that light would act in the same way if the ocean and sand were mediums that it were traveling through. This would cause light to refract.

This part of the lecture made me reflect upon the bus ride to Philly and walking in the streets of Philly.

The bus could have driven on all 25 mph roads or all 55 mph roads, but to kill time, drove on a few 25 mph roads and a few 55 mph roads to reduce the time that the trip to Philly took. I don't believe that there are any 25 mph roads that offer a direct path to Philly, but if there were, this route would not be the quickest route to Philly. Additionally, the bus could have traveled on 83 North to get to 30 East, but this would require going North before you could go East. The route the bus went was on Freysville Road (which goes East) to 83 North. Although the speed limit on Freysville is not 25 mph, it is less than 55 mph, and therefore illustrates the law of refraction because it took the shortest time to get to Philly going this way.

On the streets of Philly, it was not hard to pick up the existence of the concept of refraction. When people (mostly country grown Physics students) jay walk, they are traveling through different medium than when they cross the street when they are supposed to. When the lights signal that it is okay to cross the street, there is no traffic to speed up the process of walking across the street. However, when the traffic lights bear the signal "Do Not Walk" and people continue to walk anyway, there can be traffic approaching an intersection. In this situation, people tend to walk at a quicker pace to cross the street to avoid a car-pedestrian collision because walking quicker reduces the time required to cross the street. In this example, The angle of refraction would represent the decision-making process of whether to cross the street or not.



May 10, 2006 Nurwisah, Ron- Culture

The ability to compare city life, bus rides, and Barbie/Ken dolls to the idea of the index of refraction demonstrates that physics is everywhere.