The biggest idea of electrostatics is the idea that whether an object is positive, negative, or neutral is a matter of the object's movement of it's electrons. Protons never move, but charge is based on the movement of electrons. Similarly to what we already know about energy, electrons are not created or destroyed, just transferred. Something that really surprised me was the definition of what a neutral object is. A neutral object just has a balanced amount of electrons and protons rather than nothing at all. But this does not mean that a neutral object can't react with another object. As our class saw when we put a plastic comb that had gained a charge from the friction created by brushing hair, next to a stream of water. We saw the following result:
Why does the water seem to move towards the comb?
Because (let's say) the electrons in the comb begin to react with the protons in the water. This results in the opposite charges of the two object to repel each other which makes the protons and electrons polarize, or separate from each other.
Can a neutral and a charged object ever have a repelling force?
NO because protons and neutrons will always polarize in such a way that creates an attractive force (since only the electrons move). Either electrons are being pushed away, or being pulled towards a charged object.
Now that we understand charge, what is voltage? And how do we give charges energy, like when we "charge" a battery?
Voltage can also be referred to as Electrical Potential Energy. Lets think back to when we studied Gravitational Potential Energy (Ug). An object had potential energy when it was at a height above the earth. This makes sense because if an object is lets say on top of a cliff, it has POTENTIAL to fall off the cliff and plummet towards the ground. Same idea with voltage. Voltage gives charged objects a distance between eachother. All voltage is is building a (hypothetical) mountain of energy that gets transferred into other things. VOltage puts charges in such a place that stores energy.
Helpful analogy: What voltage does for charge is the same as what height does for Potential energy.
Greater voltage or charge means a greater electrical potential energy.
The greater the height or mass of an object means a greater Ug.
Potentia So when we plug in our ipads before we go to bed and it only has about 14% left, we plug our charger into the ipad, and the charger into some sort of wall outlet. The wall outlet only provides a certain amount of Voltage for objects. In the U.S, it is about 120V. 120V would be too much for our little iPads, so the charger only uses about 5.1V for charging. This wall outlet provides a height, or a distance between charges. Yes they are neutral, but their job is to separate charges in such a way that creates a charge.
But what determines if an ipad or any other device charges quickly or not? Whats the difference between the energy a lithium battery we put in our remote controls provides from a fancy white iPhone charger? Check this article out for more information on the advancement of our Electric Potential Energy!
A brief discourse on batteries (and the new iPad!)
A brief discourse on batteries (and the new iPad!)
