voltage - Voltage Before beginning, a little meditation. It...

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Voltage Before beginning, a little meditation. .. It might sound weird, but to actually understand voltage (aka “ potential difference ”) it is best to first review gravitational potential energy and figure out similarities between them. Understanding the parallels between (seemingly) unrelated things in physics is actually one of the best ways to learn physics. According to Newton’s 2 nd Law, if a force acts on an object it will accelerate. If you drop an object, the force due to gravity will cause it to accelerate down. At the top, we can say that the object has a high gravitational potential energy ... in fact, it has its greatest potential energy at this point. While it is falling we know that the gravitational potential energy is being converted to kinetic energy , so that at the bottom (its reference point) it has no gravitational potential energy remaining. Now if you want to move the object from its position of low to high potential energy, you must do work on the object against gravity. You would calculate it using… W = Fd and F = ma W = ma d since a = g and d = h ... W = mgh So the the work you do to change the gravitational potential energy is… E p = mgh No big surprise there; it's just our good old gravitational potential energy formula. What is important to realize is that we are specifically looking at this in terms of how much work needs to be done to increase its potential energy, from an area where it has low potential to an area where it has high potential. This change in gravitational potential energy depends on… 1. Mass of the object ( E p α m) 2. Gravitational field strength ( E p α g) 3. Height to which the object is moved ( E p α h) 10/21/2005 © studyphysics.ca Page 1 of 7 Figure 1: Gravitational potential energy
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Voltage I know that sometimes I might seem a little fixated on the history side of physics, but I have a good reasons. One is that the names that were given to ideas when they first came out might be different from the ones used today, and those older names might still have a meaning that helps us. A great example is what we are looking at in this section. .. voltage . It is sometimes still referred to by its older name, electric potential difference or just potential difference . If we follow the same ideas that we did in our meditation above, you might see that there are similarities between the gravitational potential energy described above and potential difference . Lets say you place a charge in an electric field and release it.
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This note was uploaded on 02/29/2012 for the course PHYS 227 taught by Professor Rabe during the Fall '08 term at Rutgers.

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voltage - Voltage Before beginning, a little meditation. It...

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