Electromagnetic Radiation from Cell Phones
The scintillating iPhone 7 pulsates as he calls. She picks up. Presses the phone to her face. Harmless, right? Think again. Five billion cell phones are used in the world today, and most people have no idea of the risks they pose. Research shows electromagnetic radiation and electrical signals emitted from cell phones pose a potential risk to health and can jeopardize security. But what is electromagnetic radiation? How does it work? And how can the layman protect himself or herself? The important problem of electromagnetic attenuation or reduction needs understanding and solving.
Electricity and Magnetism
Lightning flashes over New York like a dagger thrust into the Earth. Its light sears the eyes of passersby, as they reminisce what they learned in physics class all those years ago: charge, electricity, magnetism … Electricity and magnetism appear similar, interconnected. They can induce each other, and they also possess similar properties. The underlying cause of the commonality between them is a fundamental part of their existence: electric charge. Electric charge is a basic component of matter and can be positive or negative, meaning matter either possesses or does not possess electric charge. A rule about electric charge also exists: similar charges repulse while different charges attract.
However, charge is not the only proponent of lightning, and electricity and magnetism play a part as well. Electricity is essentially electric charge flux, where flowing electrons bear electric charge. In everyday magnetism, all electrons spin in the same direction, creating a magnetic field while also circumnavigating the dense cluster of protons and neutrons at the centers of atoms, similar to how the planets orbit the Sun. But what is a field? In the words of Doctor Richard P. Feynman, a field is “something which varies in position and space, and which has the dimensions x, y, z, and t,” where t is time and x, y, and z are the three dimensions of three-dimensional objects. Therefore, a magnetic field changes over time. But what induces its change?
To understand exactly what causes a magnetic field to change over time, electricity and magnetism must be understood as one. Yet, for many years, electricity and magnetism remained mathematically disconnected. Until, in 1871, James Clerk Maxwell combined magnetism and electricity into one theory of electromagnetism in four fundamental equations. Maxwell’s first equation, divD=p, introduces the concept of divD: the divergence, or exiting flow of electricity from a certain point, of a spontaneously charged electric field. Thus, the equation declares divD equals the amount of electric charge per square centimeter on the surface of an object, reinforcing the argument of the fundamental electric charge, as the amount of charge on the surface is equal to the electric current. Picture a balloon. When a person rubs a balloon against another surface, the balloon receives electrons onto itself. Afterwards, if one holds a balloon near a person’s hair, the balloon attracts the hair upwards. The attractive force results from Maxwell’s first equation as electrons create an electric field, attracting other electrons of the opposite charge.
Maxwell’s second equation is divB=0. The equation states the exiting flow of magnetism from a certain point equals zero, so magnetism is not created from any one point like a monopole, a magnetic particle having both a North and a South pole. One can see the equation proven in daily life, as the property of bipolarity is limited to only magnets.
Maxwell’s third equation, curlE=, also introduces a new idea: curl. Curl is the amount of rotational force exerting itself per area. Therefore, the equation declares the curl of an electric field equals the rate of change of a magnetic field over time, so an altering magnetic field creates an altering electric field. Imagine an uprooted house whirling in a hurricane, like in the Wizard of Oz. The force exerting itself on the house, forcing it around, is the circulation. “Curl is simply the…rate of rotation,” the amount of rotational force per area pushing the house and Dorothy in circular motion: the circulation divided by the area. In addition, if the entire hurricane shrinks without affecting the total force, then the amount of force per area forcing the house around would multiply, showing curl. The actual equation states the “rate of rotation” of an electric field equals the rate of change of a magnetic field, and as rotation is a constant change of velocity, change in the electric field causes change in the magnetic field. A negative sign is also in the equation because if otherwise, many fundamental laws of physics would be dysfunctional.
Maxwell’s fourth and final equation is curlH= + J. The equation states the curl of a magnetic field’s strength is equal to the rate of change of a spontaneously charged electric field, plus the density of the electric current, or the amount of charge flowing per volume of the conductor. In answer to the question posed earlier on, an altering electric field induces an altering magnetic field because the electric field and magnetic field follow the same principle as the hurricane analogy in the previous equation. Maxwell added J, the current density, because the electric current affects the rate of change of the electric field, hence affecting the “rate of rotation” in the magnetic field.
Overall, Maxwell’s equations revolutionized the world of physics, leaving many unconvinced and yearning to prove his equations. Some years after his theory’s publication, physicists proved it correct, leading to the scientific community embracing his laws and using them to explain the phenomena of the electromagnetic wave.
The Electromagnetic Wave
What is an electromagnetic wave? An electromagnetic wave is simply a wave of radiation made up of an electric field and magnetic field, vibrating and spreading out in all directions while propagating, or travelling, through anything. It is like a thrown glow-in-the-dark ball, travelling forwards yet radiating light in all directions. Combining Maxwell’s third and fourth laws creates an electromagnetic wave in the following way: changing an electric field creates a changing magnetic field; a changing magnetic field creates a changing electric field. Therefore, the fields induce each other continuously, creating a propagating electromagnetic wave. The electric and magnetic fields forming electromagnetic waves are orientated so they are perpendicular to each other. These fields travel with the same velocity as of the wave, at a speed equal to the speed of light.
In addition to measuring the speed of electromagnetic waves, the same for all waves, one can measure frequency, wavelength, V/m (Volts per meter), and µW/m2 (Microwatts per square meter). Frequency is a measure of how many wave crests, the highest points on a wave, pass a reference point in a second. It is measured in Hertz (Hz) where 1 Hertz is equal to one wave crest per second. Likewise, 100 Hz is equivalent to 100 wave crests per second. In addition, a wave’s frequency corresponds to its energy: a higher frequency means a higher amount of energy. Wavelength is a measure of the distance, in units of length, between the crests of electromagnetic waves. Wavelengths can range from smaller than an atom to the size of a tree, and beyond.
Wavelength and frequency are related: the less distance between wave crests, the more wave crests can pass a reference point in a second. In other words, as wavelength decreases, frequency increases: a wavelength of equal to or greater than 1,000 kilometers corresponds to a frequency of equal to or less than 100 Hz; a wavelength of one to 100 meters corresponds to a frequency of 1 million-100 million Hz; a wavelength of 0.01 meters corresponds to a frequency of 10 billion Hz. Therefore, a wave as long as a meter stick has around 100 million wave crests propagating, or traveling, per second.
Volts per meter is the unit of measurement of the electric field strength of electromagnetic radiation, and in particular, low frequency radiation. V/m measures the intensity of an electrical signal transmitted by electromagnetic radiation, and does not measure any thermal energy. µW/m2 is a measure of Power Flux Density, and is “measured by averaging the power over time,” making µW/m2 measurements better for studying thermal energy transformation.
The broad topic of electromagnetic radiation is divided into two categories: ionizing and non-ionizing radiation. Ionizing radiation is dangerous, having the smallest wavelength and the largest frequency. It consists of gamma rays, X rays, and a few ultraviolet waves. In addition, the harmfulness of ionizing radiation is the reason why one always wears a protective cover to attenuate the electromagnetic radiation when taking an X-ray. These waves are so potent because they have the potential to “knock electrons out of an atom” because of the high energy they possess, according to Ruth Netting of NASA.
Non-ionizing radiation is radiation with the largest wavelength and the lowest frequency in the electromagnetic spectrum. It includes radio-frequency radiation, with a wavelength of one to one hundred meters, microwave radiation, ELF radiation, the light spectrum, and a section of ultraviolet radiation. Incident non-ionizing radiation encountering atoms increases their oscillations, also known as vibrations. An example of non-ionizing radiation in action, a microwave oven, uses the radiation to make molecules of water oscillate quicker and create heat, in order to warm food. Another way people utilize the electromagnetic wave is in the field of telecommunication, particularly with cell phones.
Cell phones at their simplest manipulate electromagnetic radiation to call others and are used en masse: around five billion cell phones worldwide, according to the Telecommunication Union and the National Cancer Institute. In 2014, the estimate of just cell phone users in the United States topped 327.5 million people, according to the Cellular Telecommunication and Internet Association and the National Cancer Institute. National Cancer Institute statistics illustrate a tremendous growth in users: at the beginning of the twenty first century, only 110 million cell phone users existed in the United States. In fourteen years, the number of users has tripled, like Pokémon Go’s rapid escalation into a worldwide game.
Cell phones communicate with each other using signals during calls, texts, e-mails…any form of communication. “A signal is anything…that can be used to send information,” according to Andrew Champagne. Examples of signals are waves, alphanumerical series, and motions. Another type of signal, a carrier signal, transmits information signals. In cell phones, the information signals are electrical signals, while the carriers are radio-frequency waves. Two types of signals transmit information: digital, the modern, widespread signal, and analog. Separating sound waves into smaller sections of data creates binary bits, information expressed as 1’s or 0’s, which form digital signals.
However, are signals sent from phone to phone? No. Cell phones have the word ‘cell’ in because of the method of communication within the networks they utilize. Telecommunication corporations separate the areas where they provide service into areas of lesser size known as cells. Within every cell lies a base station. Within the respective cells of the base stations, they transmit electrical signals between cell phones, via themselves. When calling, the base station receives signals from the cell phone and forwards them to a switching center, and sometimes the telephone network. From there, the signals are transmitted to the base station of the called phone’s cell and then to the phone itself. When receiving a call, the signal goes through the process outlined above. When in the midst of a phone call and one exits one cell and enters another, the transmission of electrical signals changes to the base station in the new cell. No intermission takes place as the network just alters the location of transmission. Failed calls are a result of large distances between the phone and the base station, or an obstruction between the phone and the base station, such as a tree, decimating the electric signal strength.
Cell phones have become smaller and smaller over the years, improving just like their signals and communication. Presently, the external parts of a phone are the buttons such as the power button, and the screen, allowing the user to manage the phone with contact. Internally, two key parts are the microphone, which absorbs sound waves, and the speaker, which emits sound waves. The battery is another integral part of a phone because it provides a current, allowing the phone to operate. The circuit board, where numerous silicon semiconductors lie, interconnects all components of the phone with circuits where current flows. Each semiconductor incorporates transistors and other semiconductor mechanisms into its functioning. They have various different functions: RAM (short-term memory), ROM (long-term memory), CPU (processor), etc. A SIM card, another part of a cell phone, provides information on the user to the telecommunication system and is an abbreviation of ‘subscriber identity module’.
Also in a phone is the antenna, a necessary feature involved in the transmission of electrical signals and their carrier signals. Antennas emit energy in the form of electromagnetic radiation when electrical current flows to them. The circuit loses the emitted energy, meaning the antenna must have resistance, known as radiation resistance. As radiation resistance creates radiation emissions, a correlation between radiation resistance and the quantity of electromagnetic radiation emitted exists: the more radiation resistance, the more electromagnetic radiation emitted. The formula for radiation resistance is E=kC2. Here ‘E’ is the energy emitted, ‘k’ is a constant, and ‘C’ is the current flowing to the antenna. The formula shows the electric current flowing to the antenna causes the radiation emissions: the more current flowing to the antenna, the more radiation emitted.
The antenna transmits digital signals to the base station, but received sound waves from a person speaking are transformed first into analog signals, before digital signals. In addition, when the cell phone receives sound as a digital signal, a system transforms it into an analog signal before the sound is emitted and heard. The system performing the above transformation is CODEC, a collection of interconnected components of a phone containing at least one semiconductor chip. It has its name from ‘COder’ and ‘DECoder’, since these are the tasks it performs. Overall, cell phones make use of only one type of physical behavior of electromagnetic waves: transmission. However, many more exist, playing key roles in our use of electromagnetic radiation.
Behavior and Attenuation of Electromagnetic Waves
All types of electromagnetic radiation have common traits ensuring they all behave in the same ways upon contact with matter. Waves can undergo transmission, refraction, reflection, absorption, diffraction, polarization, or scattering. Any substance can perform these processes, but the factors of electromagnetic wave wavelength and the structure of the substance determine their effectiveness.
Transmission, the propagation of electromagnetic radiation through a substance, is the first physical behavior of electromagnetic radiation. It is slower in denser mediums: for instance, transmission through water is slower than through air. Refraction, another physical behavior of electromagnetic radiation, occurs when electromagnetic waves travel through a substance and alter their direction of motion because of the change in transmission speed. The change in transmission speed results in acceleration, inducing refraction, so different accelerations correspond to different angles of refraction. Think about drinking a clear liquid through a straw. Looking at the straw in the liquid, it will appear bent, even though upon removal and inspection, it is straight. Refraction causes the phenomenon, because transmission through air is faster than through the liquid and so the light will refract, changing direction. Reflection, the third physical behavior of electromagnetic radiation, occurs when a surface reflects, or throws back the radiation. Smooth surfaces such as mirrors reflect most incident radiation, while lighter substances reflect more radiation than darker substances.
Absorption, the fourth physical behavior of electromagnetic radiation, occurs when radiation transfers energy to the substance transmitted through, reducing the radiation’s frequency and creating heat. Interestingly, darker substances absorb more radiation compared to lighter substances. If a black car is left parked in the open on a sunny day for a few hours, it will be hotter than a white car in similar circumstances.
Furthermore, the less transparent a substance, the more electromagnetic radiation it can absorb. For example, wood, a substance nearly impervious to light, absorbs electromagnetic radiation. On the other hand, glass, a translucent substance, cannot absorb much electromagnetic radiation so glass objects like windows let through light. Transparent substances also cause a “spread or convergence of the beam” of electromagnetic radiation transmitted through them, according to William West of McGraw-Hill Education.
Absorption is a complex behavior of electromagnetic radiation, yet one law explains it all: Beer’s law. Beer’s law states the relationship between the factors affecting absorption:
The law holds true where ‘I’ is the intensity of the electromagnetic radiation after absorption; I0 is the intensity of the electromagnetic radiation before absorption; ‘e’ is the natural base, approximately 2.71828; ‘k’ is the constant for the material used, accounting for transparency; ‘c’ is density; and ‘d’ is the thickness of the material. The law states the denser, the thicker, and/or the more transparent the substance, the more electromagnetic radiation absorbed.
Diffraction, the fifth physical behavior of electromagnetic radiation, occurs when electromagnetic radiation warps and extends, travelling around an obstruction in its path. The warping is most noticeable when a wave of electromagnetic radiation diffracts about an object similar in size to the wavelength of the wave.
Polarization, the penultimate physical behavior of electromagnetic radiation, occurs when a material induces the oscillations of electromagnetic waves to propagate in only one direction, changing the wave from having multiple oscillation directions to only one. Imagine forcing a star with many points through a narrow opening. The opening would fracture all directions the star extends itself in except one, ‘polarizing’ the star.
Scattering, the final physical behavior of electromagnetic radiation, is similar to reflection as in both, surfaces reflect incident electromagnetic radiation. However, scattering differs as the waves are reflected in various ways to different locations; in reflection, all waves are reflected in one way. Furthermore, the composition of the substance scattering the radiation and the radiation wavelength determine the quantity of radiation scattered: shorter wavelengths of radiation are scattered more than longer wavelengths. One example of scattering is the color of the sky: the atmosphere scatters blue light more than other light, so the sky is blue. To conclude, electromagnetic waves behave in multiple ways upon contact with matter. However, all of these behaviors, except transmission, are part of one broader topic: attenuation, the reduction of electromagnetic radiation, because all behaviors reduce the total electromagnetic radiation propagating through a substance. Even so, certain materials can attenuate electromagnetic radiation better than others can.
Attenuating Electromagnetic Radiation With Copper, Aluminum, and Latex Rubber
Like the swathes of people who run for government offices every year, hundreds of products pour out into the marketplace every month, all with the same claim: they attenuate electromagnetic radiation better than the others do. But how does the world know which candidate will stay true to their word, which product they can trust, if they are not scientifically backed? Copper, aluminum, and latex rubber are widespread in these products and are often claimed as effective in the attenuation of electromagnetic radiation.
Copper and aluminum are effective materials for attenuating electromagnetic radiation emitted from electronic gadgets, using absorption and reflection to reduce the radio-frequency radiation. However, if copper and aluminum are attenuation goldmines, latex rubber is a shallow pit of fool’s gold. Latex rubber is futile in radiation attenuation because “natural rubber is a polymer of isoprene,” a hydrocarbon made up of five carbon and eight hydrogen atoms, according to Geetika Arora. The density of hydrogen is 0.0000899 grams per cubic centimeter, and the density of carbon is 2.26 grams per cubic centimeter, making the approximate density of isoprene, and hence latex rubber, 0.8693 grams per cubic centimeter. According to Beer’s law, denser substances absorb more electromagnetic radiation compared to less dense substances. Therefore, comparing the density of latex rubber, 0.8693 g/cm3, to the density of aluminum, 2.7 g/cm3, and the density of copper, 8.92 g/cm3, aluminum and copper are better attenuators of electromagnetic radiation.
Another important tool in determining attenuation effectiveness of materials is a graph, created by J. Tuszynski. Tuszynski’s graph models the logarithm of Photon Mass Energy-Absorption Coefficients in cm2/g, or in simple terms, the ability of the elements to absorb electromagnetic radiation. The absorption coefficient states the amount of incident radiation absorbed per gram. In the graph, as the atomic number of the element increases, its ability to attenuate electromagnetic radiation increases. Carbon has an atomic number of six and Hydrogen has an atomic number of one, meaning latex rubber barely attenuates electromagnetic radiation and is totally unable to do so where the radiation is roughly greater than 0.009 MeV, hardly any radiation at all. Meanwhile, aluminum’s atomic number is thirteen and copper’s atomic number is twenty-nine, showing they better attenuate electromagnetic radiation. Overall, to disperse the myths surrounding the ability of materials to attenuate electromagnetic radiation, copper is theoretically the best material out of these three, with aluminum and latex rubber following. Knowing which material is best is key in selecting one to attenuate electromagnetic radiation in the context of the real world and its problems.
Health and Security Reasons to Attenuate Electromagnetic Radiation
In the real world, three main problems associated with the use of cell phones and other electromagnetic radiation-emitting items are health risks, security, and disruption. Health risks are the most prominent threats surrounding cell phones. Biological cells closest to cell phone antennas absorb emitted radiation. Therefore, multiple studies were done on the effects of electromagnetic radiation emitted from cell phones on humans and other animals. The results varied and were inconclusive. In review of all of these studies, the International Agency for Research on Cancer’s chosen specialists concluded cell phones could cause cancer.
The American Cancer Society, another health organization, believes a slight correlation exists between exposure to radio-frequency radiation and the risk of cancerous tumors forming. However, in their opinion, more experimentation is necessary for a final conclusion. The National Institute of Environmental Health Sciences goes further, declaring no correlation exists between using a cell phone and any harmful health effects. Nevertheless, the National Institute of Environmental Health Sciences has agreed with the American Cancer Society as they both believe more evidence is necessary to form a final conclusion.
The United States Food and Drug Administration declares most studies done on humans do not show a correlation between radio-frequency radiation emitted from cell phones and harmful health effects. However, some experiments demonstrate a correlation, and the Food and Drug Administration maintains these experiments are false. The United States Centers for Disease Control and Prevention declares no proof exists for a correlation between using a cell phone and the formation of cancer. Concurring with their statement, the Federal Communications Commission believes that, so far, no proof of a correlation between any illness and use of any “wireless transmitting device” exists.
In 2015, the European Commission Scientific Committee on Emerging and Newly Identified Health Risks concluded no correlation between radiation from cell phones and a greater possibility of the formation of any cancerous tumors in the neck or brain. However, the organization asserts a connection will be found in the future, yet should be taken with a grain of salt. Sheer happenstance may cause the correlations, and they may lack scientific corroboration. Finally, the organization added it is painstakingly troublesome to control all variables in experimentation to say with certainty: usage of cell phones is detrimental to health. Although initial results have been inconsistent, many more will follow, possibly making new findings to determine the effects of electromagnetic radiation on health. Health risks with cell phone radiation are not the only problem though, and other just as important reasons to attenuate electromagnetic radiation await understanding.
Other reasons to attenuate electromagnetic radiation include security and the day-to-day running of electrical appliances. Various electrical appliances emit electromagnetic radiation, carrying potentially classified information others may intercept. Therefore, many corporations prefer constructing closed areas to prevent electromagnetic radiation from escaping, using its best attenuators. Furthermore, electromagnetic wave emissions of multiple electrical appliances near each other could disrupt their normal functioning, so radiation barriers are created between them to solve the problem. Overall, the risks and problems of cell phones and electromagnetic radiation, both potential and certain, need noticing.
Most of the public spends a good part of their day on the phone, or thinking about it. In all their pondering, few dare think about what actually happens in a simple phone call. The physics, nature, and behavior of electromagnetic radiation is irrelevant science to them. It was always just a phone, not a transmitter of electromagnetic radiation, nor a potential health or security risk. Imagine how the public would look differently at their cell phones, armed with the knowledge that every cell phone, in every household, in every country, is not as harmless as it seems.