Microwaves, radio waves, infrared waves, gamma rays and x-rays. Do you know what they all have in common? They are all examples of electromagnetic waves (EM waves). In this article, we’ll be tackling the concepts, definitions and applications of electromagnetic waves!
Electromagnetic waves consist of magnetic fields and vibrating electricity. This is where they transmit energy across space or through matter. There are three main properties you should know about electromagnetic waves:
- Speed: All electromagnetic waves travel at the same speed. This speed, known as the speed of light, is around 300 million metres per second. These waves are neither deflected by a magnetic field or an electric field, but are capable of showing diffraction or interference.
- Frequency: Also known as ‘wave frequency’, this is the number of waves that passes a fixed point in any given amount of time. The frequencies of electromagnetic waves can range between thousands of waves per second, to trillions of waves per second.
- Wavelength: The distance between adjacent waves and their corresponding peaks. The wavelengths of an electromagnetic wave can range between the length of a soccer field, to being shorter than the diameter of an atom.
Electromagnetic waves can travel through all mediums, but can also propagate through the absence of a medium (that is, in a vacuum). All electromagnetic waves are also known as transverse waves, in which particles do not move, but rather oscillate up and down on their individual equilibrium positions.
To better understand the properties of electromagnetic waves, you can simplify the relationship of wavelength, frequency and the speed of light to this equation:
Wavelength × frequency = speed of light
Electromagnetic waves are split into a range of frequencies, which is known as the electromagnetic spectrum.
The electromagnetic radiation spans multiple different ranges of wavelengths as well as frequencies. This is known as the electromagnetic spectrum. The electromagnetic spectrum is divided into 7 regions. In the order of descending wavelength, and increasing frequency and energy, they include:
- Radio waves: Emitted and received by antennas. They are used for controlling remotes and industrial heating.
- Microwaves: Radio waves with short wavelengths. Microwaves can penetrate materials below the surface and deposit their energy.
- Infrared: Divided into three parts: far-infrared, mid-infrared and near-infrared.
- Visible light: Visible light is the part of the electromagnetic spectrum in which the human eye is most sensitive to.
- Ultraviolet (UV): Exposure to UV rays can cause damage to living tissues. UV rays are also known to cause sunburns due to UV radiation on skin cells, which can lead to skin cancer.
- X-rays: X-rays are used as probes to see through objects with thicknesses.
- Gamma rays: Gamma rays have the most energetic photons, which have no defined lower limit when it comes to their wavelength. They are used for irradiation of seeds and foods for sterilisation and used in medicine for radiation cancer therapy.
Effects of electromagnetic waves
Electromagnetic radiation can cause many effects to living things and objects, including our body cells and body tissues. Let’s take a closer look at how this happens:
Ionisation is the process where an electron is given enough energy to break away from an atom. This process then results in the formation of two charged ions or particles,. Ionising radiation can be produced from artificial or natural sources.
On the electromagnetic spectrum, X-rays, gamma rays and the higher ultraviolet part of the electromagnetic spectrum are ionising. Non-ionising radiation are waves with lower frequency, longer wavelength and lower energy.
While non-ionising radiation does not penetrate deep into the tissues, they can cause damage to our skin and eyes. Ionising radiation, on the other hand, is known to cause damage to living tissues as they can cause chemical changes through the breaking of chemical bonds.
- Damage to living cells and tissue
The sun’s rays are a form of electromagnetic radiation, which encompasses a large range of frequencies in the spectrum. Ultraviolet rays from the sun are what causes effects like suntan and sunburn, as the rays can penetrate the surface layers of our skin. Radiation-caused cellular damage may also lead to cancer.
Electromagnetic waves which have higher energy, such as x-rays, can penetrate deeper into our bodies. For instance, they can pass through soft tissues, but not through hard tissues such as bone. If we are exposed to x-rays for an extended period, they could cause DNA damage as well.
Heating involves heat transfer and absorption of electromagnetic waves, whereby any material exposed to the electromagnetic radiation will heat up. One such example is microwave heating.
Electromagnetic waves play a vital role in our daily lives, especially when it comes to communication technology. This is because electromagnetic waves can transmit energy through a vacuum, or without a medium. Here are a few applications of electromagnetic waves in our lives.
- Radio waves: For communication uses, such as television communication and radio.
- Microwaves: Used in a microwave oven to heat meals, and for satellite television.
- Infrared: Commonly used in security cameras to detect intruders, or for night vision.
- Visible light: Used in optical fibres for telecommunications and medical imaging technology.
- Ultra-violet: Photochromic ink is used to counter forgery of banknotes. Banknotes with this security feature glow fluorescent under UV light.
- X-rays: Used in X-ray machines, where the rays pass through flesh to detect the bone structure, useful for detecting injuries, monitoring recovery, and so on.
- Gamma rays: These rays are used in cancer radiation therapy to kill off cancer cells.
These are just some of the key concepts, applications, and effects that you need to know about electromagnetic waves and the electromagnetic spectrum! Not only can they help to broaden your physics learning, but you’ll get to learn more about how our world operates. If you ever require further understanding of electromagnetic waves, the electromagnetic spectrum, or other essential physics concepts, then you should enrol in a physics tuition class! Having an experienced tutor ensures that you never lose your grasp of important physics concepts, and that you continue to enhance your physics learning.