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It is that part of the semester where the Right Hand Rule (RHR) comes out. Really, the best part is the students taking the tests. They make all these funny motions with their hands. That makes tests more entertaining (for me) than they usually are. What is the RHR? Suppose I have two numbers. Maybe…

Pre Reqs: electric potential, electric field, work-energy To start, remember that for a constant electric field the change in electric potential energy would be: WARNING: that is only for a constant electric field. I know you will be tempted later to use this for a different electric field, but DON’T DO IT. But if not…

Basics: Electric Potential

Pre Reqs: Electric Field, Work-Energy, Potential Energy If you are already familiar with the topics listed in the pre-reqs above, this will be uber-simple. Potential energy – short version The work-energy principle basically says: In this most basic form, the energy is just kinetic energy (if you are not going near the speed of light).…

Physics 2 refresher

So, I hear you are starting your second semester of physics. One of the cool things about physics is that the second semester still uses stuff from the first semester. Maybe you forgot some of that stuff, so here are the bare essentials you will need to get by (this is assuming you are in…

Basics: The electric field

Suppose I take a 1 kg ball and hold it near the surface of the Earth. What would be the gravitational force the Earth exerts on this ball? And I could say “g” is: The magnitude of this force would then be 9.8 Newtons. And, if I replaced the ball with a 10 kg ball,…

So, I complained about MythBuster’s explanation of relative velocity. How would I explain this? I would start by saying that velocity is relative. Here is the definition for velocity: I put the “avg” in there because it is more true. If the acceleration is zero, I could drop this. For the rest of this post,…

Pre Reqs: vectors, forces This is typically the first topic in the second semester of introductory physics – the interaction between objects with electric charge. There are 4 fundamental forces that physics typically looks at: Gravity – an interaction between objects with mass – wow, I don’t have a post on the universal law of…

DIY Force probe

I was thinking about some experiments that deal with friction and I wanted to show something with a force probe. The problem is that most people don’t have one of these. So, I decided to try and make one out of simple things. In this case, I am using some straws, a rubber band and…

Green Laser and Fluorescence

Do you have a green laser pointer? You should. They are relatively inexpensive now. What if you take your laser pointer and aim it at stuff in your house? The laser dot always looks green, right? This is actually a pretty important point about color. Suppose I have the lights on in a room and…

Physics Textbook

The following is a collection of some of my posts that can be put into a simple and quick textbook-type thingy. I am not really sure you would call this a textbook, but maybe you would. This does not include everything you would normally find in a traditional textbook, but clearly it is not traditional.…