Electronics 10 rzcoronelnapa: Voltage and Current

Today we started circuit analysis and explored the behavior of charged particles as they move, specifically along wires. Today we started with a simple experiment. We were given a battery, a light bulb, and a wire. And, we were told to find ways in which it works and doesn't. It turned out that there is a specific way in which they have to be arranged in order to make the light bulb light up. Basically they have to be touching each other and arranged in a closed circuit. There are two ways to accomplish this. One of them is on the picture below. The other is very similar. The wire touch the flat bottom of the bulb instead of the metal on the side, and the metal on the side has to be touching the battery. It would look like the picture below but with the bulb on its side and the wire touching the bottom of the bulb. Nevertheless, it turns out that there is a filament inside the light bulb that starts on the bottom of the light bulb, goes up into the bulb, and it comes down and touches the conducting metal that is on the bottom of the side. Since the filament isn't touching anything on its way, it shows that it allows a pathway for electricity to run.

As long as the wire is touching the bottom of the light bulb and the conducting metal is touching the top of the battery or the wire is touching the conducting metal and the bottom of the bulb is touching the battery, the bulb lights up. Below we wrote down the four parts that we needed to make the bulb light up.

After we got a sense of how to make the light bulb light up, we made the light shine even brighter by staking two batteries and the light bulb on top of each other as shown in the picture. Then we connected the bottom of the battery to the light bulb with a wire.

So, what happens in the circuit? And how does it work? Prof. Mason said that the battery creates a difference in electric potential, and that creates an electric field in the circuit. Since the wires are made of metals that have free electrons. We concluded that there are electrons moving in the circuit due to the electric field caused by the battery. Nevertheless, after a certain time of continuous use, the bulb stops shinning, meaning something gets used up. Since electrons are moving within a closed circuit, they are not lost. But since the battery made them move, the battery gives them energy. Hence, it is the energy that they carry that gets used up. Hence as it says in the picture below, the charge does not get used up. The energy is used up. This is the reason bulbs burn out.

Then we started investigating the energy that the battery gives in the closed circuit by making an analogy. We compared the flow of electrons to the flow of water while they are in closed circuits. The battery does the same as the water pump by elevating the energy of the water and having it release its energy along its path back to the water pump.

Below are three galvanometers that have been used throughout history. The black one was built around the 1950s and was made out of plastic that was made at the time. The same goes for the other ones. Each is made of materials that were popular in their own times and resemble styles from those eras as well. For example, the red one is made with plastic that is a lot more modern.

Below is a picture of the galvanometer we used to measure the current in our circuit. It read 100 mA. The circuit consisted of a battery, the galvanometer, a bulb, and the switch.

Prof. Mason was showing the class how it's done.

Below is the circuit that Prof. Mason built.

Below is the calculation for the velocity of particles across the cables in a circuit.

Prof. Mason set up a circuit and read an output of 2.0 V and 0.31 A. Then, connected it to Logger Pro to record data and prepare

The computer actually registered 0.587 V and 0.0897 A in the circuit. Then he connected it to the resistance board where there were three cables each with a different resistance.