Circuits Lab

Yesterday we worked for a few minutes doing a brief circuit lab. We did three different circuits, a lemon battery, a solar panel, and a hand crank.
First, we examined the solar panel circuit. This circuit works by utilizing semi-conductors such as silicon. Using the silicon (and like materials) allows for a lattice life structure due to the orginization of the electrons. As Silicon has four electrons, the different molecules share the electrons equally in an attempt to reach that more stable level of eight electrons. However in the silicon that is utilized, there are "impurities" which dont have the four valence electrons of silicon. These have either excess or fewer electrons which allow the solar panel to work. The sunlight, in the form of photons, enters the semi-conductor and this inflow of energy knocks off some of the electrons of the impurities. These "knocked" off electrons create a current, as desired. As we moved the panel closer to the light source, the voltage increased because of a greater exposure to light.
Second, we worked with the lemon battery. This was made up of a lemon, a copper penny, a nail, and a wire which connects the penny and nail. When stuck in the lemon, both the nail and penny are exposed to the citric acid which is in the lemon. The acid steadily eats away at the molecules which make up the nail and this chemical reaction releases the excess electrons. The excess electrons bond with the hydrogen ions in the acid. The electrons in the copper want to do the same thing, but find it easier near the acid eaten nail. So they flow through the wire, creating a current.
We finished up with the crank shaft. This circuit works by the movement of a magnet through coils of wire. The magnet is moved by the hand-powered crank. The motion of the magnet creates a movement in the magnetic field in the coils and through induction a current is created to counter this change. In order to counter this change in magnetic field, a current is created in the coils. The magnetic field is constantly changing, so depending on where the magnet is at any given point, the current will flow to the left or right in the coils. As the current flows it will eventually leave the coils and enter the resistor (the light bulb).