Ohm’s Law is V = I * R or in some cases I = V / R. The next two laws were established by a German physicist by the name of Gustav Kirchhoff. Kirchhoff’s first law is his voltage law. Kirchhoff’s Voltage Law (KVL) states that around any loop in a circuit, the voltage rises must equal the voltage drops. The next law that Kirchhoff introduced was his current law. Kirchhoff’s Current Law (KCL) states that the total current entering a junction must equal the total current leaving the junction. These laws, however, cannot be proven or tested without the aid of a multimeter. A multimeter is an instrument designed to measure electric current, voltage, and usually resistance, typically over several ranges of value. The multimeter has different programs to measure voltage, current, resistance, etc. produced from one of two types of circuits.
The first type of circuit is a series circuit. A series circuit is a circuit in which the components are arranged end to end in such a way that the electric current flows through the first component, through the next component, and so on, until it reaches the source again. In contrast, a parallel circuit is a circuit in which the has more than one resistor and has multiple paths to move along. The main purpose of this lab was to prove the laws of Ohm and Kirchhoff. On another note, being able to take part in this lab taught my partner and I the fundamental skills of constructing series and parallel circuit and using a multimeter to calculate the current and voltage of a circuit.
I believe that if we only have the basic materials to conduct electricity (such as resistors, alligator clip, cords, a multimeter, and a power source), then we can still prove the that the laws that Ohm and Kirchhoff established are in fact reliable sources for calculating data regarding certain electrical circuits. I’ve reached this hypothesis because Ohm’s laws and Kirchhoff’s two laws are supposed to be laws used for any electrical circuits. Based on this, these three laws should be able to be validated with this experiment.
– Power Source
– Alligator Clips
– 1,000 Ohms Resistor
– 10,000 Ohms Resistor
1. Assemble circuit as seen in figure 1 and set the multimeter to current 2. install series in the circuit and set the power supply to 3, 4.5, 6, 7.5 3. record number on multimeter and compare to the calculated current using Ohm’s law
Kirchhoff’s Voltage Law
1. assemble circuit as seen in figure 2 and set multimeter to volts 2. install in parallel over both resistors and set the power supply to 3, 4.5, 6, 7.5 3. record number on multimeter and see if the total voltage dropped equals voltage added
Kirchhoff’s Current Law
1. Assemble circuit as seen in figure 3 and set multimeter back to current 2. install at all three points at both junctions 3. see if the current entering the junction is equal to the current leaving the junctions
Our lab in general, went fairly well. We took our time and did not rush through this lab, so we could get the best results, but we did have some trouble with our Multimeter on more than one occasion. For example, while we were attempting to prove Ohm’s Law and Kirchhoff’s Voltage Law. The Multimeter, at first was acting up and completely just not working, but we then realized that it was not set on the correct measuring task. Then, on the same two labs, we were getting readings from the Multimeter that made no sense. It told us that the current for the circuit was 967.83 Ohms which for the type of circuit that we built, was impossible.
After fixing the problem with the Multimeter and proving Ohm’s Law and Kirchhoff’s Voltage Law, we moved onto the Current Law that Kirchhoff established. This time, the problem wasn’t the Multimeter, or the resistors, or the power supply, or anything else. It was us. We were overall a bit confused on how the circuit was created and it took a long time to eventually construct and then prove. Even though the problems were an annoyance, the lab was very insightful and taught us a lot about electric currents and circuits.
At the conclusion of this experiment, our results supported our hypothesis greatly even though our numbers were not a hundred percent on point. But there is room for error, like the fact that the power supply was not great quality and doesn’t give exactly 3 volts or 4.5 volts or any of that. Also, the resistors are not high-quality resistors and are also worn down from years of use, so they don’t give exactly 1,000 / 10,000 Ohms like we were looking for. Other sources of error included the Multimeter, which was not exact because the Multimeter rounds numbers, the Alligator clips, which are (like the power supply and resistors) not the best and shed energy, and our calculations, which could have suffered from any addition or multiplication or division error.