# Second Semester Physics Examples

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## The Origin of Convention Current (this is a link)

Convention Current as the name implies was chosen and because of a “some justifiable” reason. The reason that is going to be presented is thought to be true and is shown many times on the web. At the time of Benjamin Franklin and Paul Revere, 1776 or so, electricity was being investigated.

With the investigation of electricity, there was some initial use of electricty for something very new, beautiful and novel. It needs to be remembered that Paul Revere was a silversmith. So there were people that were discovering that when metals were plated, the precious metals ended on the objects connected to the negative plates of the batteries. Thus it would follow that whatever was flowing had to be positive. Thus positive current flow!

I use this small picture to launch into telling good things about my 5th grade teacher, Mr. Eby. The class was supposed to bring in a metal object to copper plate: My mother found the pictured shoe horn that the class plated, thus the tie to positive current flow. This shoe horn has been following me ever since 5th grade!

The Internal Resistance of a Battery/Potentiometer

This experiment is good on so many levels. As can be seen in the photograph of the board, it gives a chance to relate the circuit with the sum of the voltages in a closed loop, Kirkoff’s law to a graphical graphical analysis. In the graph the y intercept is the electromotive force (EMF) and the slope of the graph is the multiplicative negative of internal resistance of the battery.

Batteries are very much a part of today’s living: They are the way to get a portable electrical power supply, but unfortunately they give a lot of waste behind. In this photograph here is the environmental wake of rechargeable batteries. I told my Mother that I was going to show the “snake-light” and “portable power screwdriver” that my Mom and Dad gave me: A lesson that I can use this web site for is to hopefully teach the world that “propriety” sized batteries are ecologically wasteful and a waste of one’s money.

I know of several other instances of this problem: Henry Ford hit on the idea of interchangeable parts, one would think we would follow a good lead. One classic problem is when the battery in the cell phone goes bad, one is forced to buy a new phone.

## Images made with the Mirror of a Telescope on a 35 mm Camera Color Film

The Images made using a 35mm Camera Mounted on the Focal Plane of a Telescope Mirror:

September 26, 2001, a Meade LX200 was installed into the observatory. I had the oportunity to use the camera adapter on the telescope before the permanent CCD camera was installed. The parts of the camera can be seen in my astronomy examples.
I put my camera back on the telescope. Any photographer knows that a “telephoto” lens is good for the shot of the moon. The telescope has a 3048 mm focal length mirror with an f of 10. This was a opportunity to “verify” that f/10 at 1/60 second will provide an great image. So in the “interest of science” and to “illustrate the point” I happily made these images.

Example of Image formation using a 35 mm camera backof the Moon in the afternoon –“Palatino”

##### Example of Image formation using a 35 mm camera backof the Moon in the afternoon –“Palatino”

Example of Image formation using a 35 mm camera back on Jupiter

This does show that the image is very small, but still you ca project an image from a telescope mirror onto a 35 mm film plane.