The electromagnetic spectrum is divided into seven intervals frequencyof electromagnetic waves. These types produce different effects on matter, check them out:
- Infrared: Also known as hot flashes waves, transfers energy to atomsand molecules, causing them to oscillate more intensely, causing the temperature to rise.
- Visible light:can excite the electrons of atoms, causing changes in the energy levels of atoms.
- Ultraviolet radiation:carries a large amount of energy, thus, it is able to strip electrons from atoms, ionizing them.
- X ray: have the ability to ionize atoms and also produce energy transitions in the nuclei of atoms, which re-emit new x-ray frequencies.
- Gamma radiation: carry a large amount of energy and, therefore, can destabilize the nuclei of atoms, which can undergo nuclear fission .
The following figure shows the electromagnetic spectrum, note:
Examples of electromagnetic waves in our daily lives
Check out some examples of applications of the types of electromagnetic waves in phenomena and technologies present in our daily lives:
- Radio waves : are used in the transmission of TV, radio, GPS and cell phone signals.
- Microwaves : are used in ovens that heat food. This heating happens thanks to the resonance between water molecules and microwaves with a frequency close to 2450 MHz.
- Infrared : it is not visible to the naked eye, however, there are security cameras that make very clear night images by capturing it.
- Visible light : is that which excites the sensory organs of vision , allowing us to see the world and all things around us. This light spans the shades of red, yellow, green, orange, yellow, green, cyan, blue, and violet.
- Ultraviolet: it is not perceived by the human eye, however we are constantly exposed to this type of radiation thanks to solar radiation. Because it is ionizing radiation, ultraviolet light can cause genetic mutations in skin cells, leading to skin cancer..
- X-rays: are ionizing radiation , with high penetration power, and widely used to perform imaging tests, such as radiography and tomography. In addition, they can be used to fight cancer through radiotherapy .
- Gamma rays : These are the most energetic electromagnetic waves in the entire electromagnetic spectrum. They are produced by nuclear reactions and are highly ionizing, so they are used for analysis of the internal structure of solids, sterilization of medical products and utensils, etc.
Definition of electromagnetic waves
They are oscillatory phenomena that transport energy and do not need a physical medium to propagate . Electromagnetic waves are produced by electric fields and magnetic fields that are oscillating and perpendicular to each other. Their types are classified according to their frequency range, according to the electromagnetic spectrum.
Electromagnetic waves were first described mathematically in 1864 by the Scottish mathematician James Clerk Maxwell, through a set of equations known as Maxwell’s equations .
The definitive proof of the existence of electromagnetic waves came around 1880, at the time, the German physicist Heinrich Hertzproduced, detected and proved the existence of radio waves , which moved at the speed of light and had all the characteristics of the waves described in the Maxwell’s works. If you are more interested in the topic of this topic, read: Electromagnetic waves .
Characteristics of electromagnetic waves
Let’s list some of the characteristics of electromagnetic waves, check them out:
- They do not need a physical medium to propagate. In a vacuum, they travel at the speed of light — 299,792,458 m/s.
- They are transversal and are direction characterized by the fact that the in which they propagate is perpendicular to the direction of the stimulus that produces them.
- They propagate in the three directions of space, therefore, they are waves of three-dimensional propagation.
- They can undergo different types of phenomena, such as reflection , refraction , absorption, diffraction , interference, dispersion , scattering, polarization , etc.
- Their propagation speed depends exclusively on the medium in which they propagate, since each medium has a certain refractive index.
- According to the wave/particle duality , proposed by the German physicist Albert Einstein in his 1905 paper explaining the photoelectric effect , light can behave both as a wave and as a set of particles called photons.
In addition to these, there are physical characteristics that distinguish one electromagnetic wave from another, check out:
- Amplitude: it is related to the intensity of electromagnetic waves, that is, it depends on the amount of energy that the wave is able to transfer each second.
- Velocity: depends on the refractive index at which the electromagnetic wave propagates. In a vacuum , all electromagnetic waves travel at the speed of light.
- Frequency: is the measure of oscillations that the electric field makes every second. According to the SI , this unit is -1 , known as Hertz ,
- Wavelength : refers to the length that a wave travels until it completes an oscillation of the electric field. The wavelength is the distance between two crests or two valleys of the electromagnetic wave.
Formula of electromagnetic waves
The main formula used for electromagnetic waves is the one that relates propagation speed, wavelength and frequency, note:
v – propagation speed (m/s)
λ – wavelength (m)
f – frequency (Hz)
Solved exercises on electromagnetic waves
Question 1) Choose, among the following alternatives, the one in which there are exclusively electromagnetic waves:
a) x-rays, gamma rays, ultraviolet
b) radio waves, infrared, ultrasound
c) visible light, ultraviolet, sound
d) infrared, radio waves, sonar
e) ultraviolet, gamma rays, infrasound
Template: Letter A
Electromagnetic waves are formed by the oscillation of electric and magnetic fields, are transverse, three-dimensional and propagate through a vacuum. There are types of electromagnetic waves: radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma radiation. Therefore, the correct alternative is letter A.
Question 2) These are characteristics capable of distinguishing one type of electromagnetic wave from another:
a) intensity, velocity, area, length, force
b) amplitude, disturbance, propagation, direction, sense
c) amplitude, velocity, frequency, wavelength
d) pitch, intensity, timbre, speed, polarization
Template: Letter C
The most general characteristics inherent to electromagnetic waves are wave amplitude, propagation speed, oscillation frequency, and wavelength. Therefore, the correct alternative is letter C.