Introduction

Relevance of the Theme

The study of waves is of utmost importance for Physics and our daily lives. After all, they are present in everything, from sunlight that allows us to see, to radio signals that keep us connected to the world. In the context of radiations, it is essential to understand the risks and benefits associated with them, as we are exposed to different types of radiation all the time. Understanding these concepts provides a solid foundation for the comprehension of more advanced topics, such as Quantum Physics, and enables us to make informed decisions about our well-being.

Contextualization

The study of waves and their characteristics is an integral part of the High School Physics curriculum. After learning the fundamentals of waves and their properties, students will now be introduced to a topic that extends beyond the visible spectrum: radiations. This is a multidisciplinary topic that involves knowledge from Physics, Biology, and Health. Let's explore the different types of radiations, how they interact with matter, their risks, and benefits. It is important to highlight that this discussion is not limited to the classroom environment - it is directly related to our daily life, including the use of cell phones, solar radiation, and even nuclear energy. Now, let's dive into this vast and fascinating universe of waves and radiations!

Theoretical Development

Components

• Electromagnetic Waves: These are waves that do not require a material medium to propagate. They are formed by oscillating electric and magnetic fields, which oscillate perpendicularly to each other and to the direction of wave propagation. The spectrum of electromagnetic waves is vast and ranges from radio waves to gamma rays.

  • Electromagnetic Spectrum: It is the distribution of energies of electromagnetic waves, which includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each type of wave has a characteristic wavelength and frequency, which determine its properties.

  • Electromagnetic Waves in Daily Life: Electromagnetic waves are everywhere: they are emitted by our electronic devices, are the basis for information transmission in radio and television signals, and even allow the visualization of our bodies in medical exams such as X-rays and magnetic resonance imaging.

• Ionizing and Non-ionizing Radiations: Radiations, as mentioned above, are a subset of electromagnetic waves. They are classified into ionizing and non-ionizing, depending on their energies.

  • Ionizing Radiations: These are electromagnetic waves with high energy, capable of removing electrons from their atoms, making them ionized. Examples include X-rays and gamma rays. Due to their high energy, these radiations have the potential to cause damage to biological tissue.

  • Non-ionizing Radiations: These are electromagnetic waves with low energy, which do not have enough energy to ionize matter. Examples include microwaves, visible light, and radio waves. Although they are less harmful to biological tissues than ionizing radiations, there is still a need to monitor and control their exposure.

Key Terms

• Ionization: Process by which an atom or molecule loses or gains electrons, becoming positively or negatively charged. This can be caused by ionizing radiations.

• Radiological Risk: It is the potential risk to human health resulting from exposure to radiations. This risk is assessed considering the absorbed radiation dose, the type of radiation, and the sensitivity of the irradiated tissue.

• Dosimetry: It is the measurement and evaluation of the radiation dose absorbed by a tissue or organ of the human body. It is an important tool for the assessment of radiological risk.

Examples and Cases

• Cases of Use of Radiations in Medicine: Ionizing radiations, such as X-rays and gamma rays, are used in various medical techniques and procedures, such as radiography, computed tomography, and radiotherapy. These techniques demonstrate the usefulness of ionizing radiations, but also the potential risks involved.

• Safety Protocols in Nuclear Industries: Industries operating with nuclear energy, such as nuclear power plants and research laboratories, follow strict safety protocols to minimize the exposure of workers and the population to ionizing radiations. This includes individual protection measures, dose monitoring, and environmental surveillance.

• Impact of Solar Radiation on Earth: Solar radiation is a mixture of ionizing and non-ionizing radiations, and plays a fundamental role in maintaining life on Earth. However, excessive exposure to solar radiation, especially to ultraviolet rays, can lead to serious health damages, such as skin cancer and cataracts.

Detailed Summary

Key Points:

• Electromagnetic Waves: Fundamental for the generation and propagation of energy. Their dual nature (particle and wave) must be understood. They do not require a material medium to propagate, being able to travel in a vacuum.

• Electromagnetic Spectrum: Encompasses a wide range of waves, each characterized by its frequency and wavelength. Each interval of the spectrum has distinct uses, risks, and benefits.

• Ionizing and Non-ionizing Radiations: Understanding the difference between these is crucial. Ionizing radiations, high energy, have the potential to damage biological molecules through ionization, while non-ionizing radiations, low energy, can cause molecular excitations and vibrations.

• Ionization and Radiological Risk: Ionization is the critical process by which ionizing radiations can cause biological damage. Radiological risk depends on the radiation dose and tissue sensitivity.

• Dosimetry: The use of instruments to measure the amount of radiation absorbed by a tissue or organ. Instrumental for the assessment of radiological risk.

Conclusions:

• Everything is Radiation: From the light we see to X-rays in the hospital, radiations are everywhere. Understanding the difference between types and their effects is fundamental.

• The Importance of Radiological Safety: Due to the potential risks associated with radiations, radiological safety is a fundamental discipline in areas such as medicine, industry, and nuclear energy.

• Benefit-Risk Balance: The use of radiations in medicine, for example, is a matter of balancing diagnostic and therapeutic benefits with potential risks.

Exercises:

1. Electromagnetic Spectrum: List the intervals of the electromagnetic spectrum, describe the physical characteristics of each interval, and give two examples of uses and one example of risk or damage associated with radiations from that interval.

2. Risks and Benefits of Radiations: Give examples of two distinct everyday situations where exposure to radiations (ionizing or non-ionizing) can be beneficial and two situations where it can be harmful. Justify your answers.

3. Dosimetry and Radiological Safety: Explain the concept of dosimetry and discuss the importance of applying this concept in the practice of radiological safety. Offer an example of a dosimetry instrument and its application in a radiological safety scenario.