Experimentation and Electricity

by Prof. André Astro 20 Nov

One of the most popular content in Enem (Brazilians SAT’s), in the physics test, is electricity. More specifically, in the last 5 years, approximately 20% of the issues were somehow related to Ohm’s laws.

Graph of the content that fell most in Enem in the last 5 years (2014 to 2018).

This shows, considering that Enem charges a lot of everyday physics, the importance of this content not only for the classroom, but for life. The great thing for us physics teachers who love experimentation is that electrodynamics opens up a lot of possibilities for demonstrating, experimenting, making mistakes and getting it right, as well as being enchanted by the content that drives our daily lives. After all, learning about electricity and how to handle it correctly is a public knowledge. In Brazil, on average, two people die each day as a result of electricity, either from shock, lightning or short-circuit fires.

The Importance of Ohm’s Law

In 1827, a German physicist and mathematician named Georg Simon Ohm developed the most fundamental law of electricity. The mathematical equation resulting from this law joins voltage and electric current to the properties of a conductor in a circuit, also defining what we call resistance.

Ohm’s law triangle, a creative way to show the equation to students.

Since then, with the evolution of electrical and electronic components, their utility has only increased. For example:

Electric kettles and irons control the amount of current flowing through them, and therefore the amount of heat needed to heat it, through Ohm’s Law.

The direct current power supply, mobile phone chargers and laptops provide variable output voltage based on the resistance of the device, all controlled by Ohm’s Law. Fuses, circuit breakers, fans, heaters are numerous examples in our daily lives.

The Importance of Experimentation in Electricity

Experimentation is a fundamental process for any and every area in education. For John Dewey, an American philosopher, learning is an action-based social practice. With that in mind, I challenge our reading teachers with a question: What if, instead of teaching about Ohm’s law, we would, in a guided activity, have them follow Ohm’s own steps, testing, measuring, and coming to himself? just in the same conclusion as Ohm?

The Azeheb’s Electricity Set (Basic) brings this possibility and many others.

Eletricity Set (Basic)

Ohm measured the voltage and current in circuits with different materials, the kit brings in addition to the test board and multimeters, various resistors, LEDs, and mini lamps of different wattages, the circuit possibilities for this part of the experiment are many. Let them find out for themselves that it is necessary to close a circuit for current to flow or that they can control the current flowing through the circuit if they change the total resistance of the circuit. Encourage them to use the key to control a light bulb. Let them burn a led and take the opportunity to introduce the concept of resistors and what they are used for. Challenge your students to find out what the potentiometer is for and how it works. “Children do not come to school as a blank sheet, but as an intensely active conscience and the task of education is to take over and guide it” (Dewey 1899, p.25) 1.

Resistors Association

Once the whole initial part is grounded with the same materials, it is possible to visually explore the series and parallel resistor associations. The practical-theory-everyday transition, not necessarily in this order, is one of the most powerful tools in education. Taking a bit of the concepts of neuroscience, this kind of activity reaches not only the most visual, as well as auditory students, but also the synaesthetics students.

The manual that comes with the kit offers several possibilities for resistor association, but the possibilities go beyond that. Draw mixed-association circuits on the board, increasing the level of complexity, and challenge your students to set up the circuit in practice. Take the practical data and compare it with the real. Demonstrate the Wheatstone Bridge. Show what a short circuit means.

For the most advanced classes, this is great content for developing critical / scientific ability as it gives you the ability to graph, practice linearization, error calculation, obtain an equation through experimental data, and precision analysis of instruments and measurements.

Final Consideration

This text does not exhaust the possibilities of what the Kit is capable of, one can further explore the operation of diodes, capacitors, Kirchhoff Laws, and more. It is just a provocation and an incentive to differentiated practices in one of the most present content in college entrance exams in any region of Brazil and in the National High School Exam. Electricity rules our daily lives. As physics teachers, we take advantage of this to give meaning to learning this very important content.

1 The school and society, 1899. In: SOUTHERN ILLINOIS UNIVERSITY. Early works of John Dewey, v. 1. Carbondale: Southern Illinois University Press, 1976. (Collected works of John Dewey). p. 1-109.

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