Contextualization

Theoretical Introduction

The First Law of Ohm, a fundamental principle of electricity, states that the current flowing through a conductor between two points is directly proportional to the voltage applied to those points. Mathematically, the law is expressed through the equation V=IR, where V is the potential difference, I is the electric current, and R is the resistance.

Resistance is an intrinsic characteristic of materials and impedes or hinders the passage of electric current. It depends on the type of material, length, cross-sectional area, and temperature. Resistance decreases with the cross-sectional area and increases with length - meaning a thicker and shorter wire will have lower resistance compared to a thinner and longer wire of the same material.

Electric current is the flow of electrons through a conductor. The current is caused by a potential difference (or voltage) between two points in a circuit. Voltage is a force that "pushes" the electrons through the circuit, and resistance is a force that "hinders" the electrons.

Context and Importance

Ohm's Law is an extremely relevant concept present in our daily lives, even if we often do not notice it. It describes the operation of various electrical devices we use every day, such as refrigerators, air conditioners, televisions, showers, hair dryers, lamps, computers, cell phone chargers, and many others.

Moreover, Ohm's Law has applications not only in electricity but in various areas of science and technology such as electronics, telecommunications, and computing. It is essential for designing and manufacturing electronic circuits, which are the basis of all modern electronic devices. Understanding Ohm's Law is also the first step to understanding more complex concepts such as electrical energy, power, and capacitance.

Practical Activity

Activity Title: Ohm's Law in Practice - Building and Testing an Electrical Circuit

Project Objective

Develop a deep understanding of the First Law of Ohm and its practical applications by building and manipulating a simple electrical circuit. During the process, students will apply theoretical concepts of Physics and Mathematics, work in teams, solve practical problems, and develop documentation and presentation skills.

Detailed Project Description

This practical project is divided into two phases: the circuit construction phase and the testing and measurement phase. In both phases, students will have to actively collaborate and apply knowledge of Physics and Mathematics. The project should be developed in groups of 3 to 5 students and is estimated to take around 15 hours in total for each student.

Phase 1: Circuit Construction

Students should design and build a simple electrical circuit on a breadboard consisting of a power source, a resistor, a switch, and a voltmeter and ammeter for measurement.

Phase 2: Testing and Measurements

Once the circuit is built, students should perform a series of tests and measurements to confirm the First Law of Ohm. They should vary the voltage and resistance in the circuit and measure the resulting current.

Necessary Materials

• Breadboard
• Conductive wires
• Variable voltage source
• Set of resistors
• Voltmeter
• Ammeter
• Switch

Detailed Step-by-Step

1. Start with the planning phase. Draw your circuit before starting to assemble it. Remember that the circuit should include a voltage source, a resistor, a switch, and places to connect the voltmeter and ammeter.
2. When the drawing is ready, start assembling the circuit on the breadboard using the conductive wires.
3. Connect the voltage source, resistor, and switch in the circuit according to the drawing.
4. Connect the voltmeter in parallel with the resistor and the voltage source. Connect the ammeter in series in the circuit.
5. With the circuit ready, start the testing and measurement phase. Note the initial voltage provided by the voltage source and the resistance value.
6. Close the circuit (turn on the switch) and take the first voltage and current measurements.
7. Change the voltage provided by the source and/or the circuit resistance and take new measurements. Repeat this step at least 5 times.
8. With these measurements in hand, verify the relationship between voltage, current, and resistance. Do they confirm the First Law of Ohm?

Project Deliverables

After completing the two phases of the project, each group should produce a report documenting the process and results.

1. Introduction: Present the concept of the First Law of Ohm, its relevance, and the motivation for developing the project.

2. Development: Describe in detail each phase of the project: the construction of the circuit and the tests/measurements. Include images, tables, and graphs to illustrate the results.

3. Conclusions: Analyze the results obtained. Do they confirm the First Law of Ohm? What difficulties were encountered and how were they overcome?

4. Bibliography: List all sources consulted throughout the project.

This group work will allow students to apply concepts learned in the classroom to a real project, improve their teamwork skills, learn to manage time efficiently, improve communication skills, develop critical thinking and problem-solving skills, and finally improve personal proactivity.