We have all seen a form of light – but there is much more to it than meets the eye. Light is electromagnetic radiation that travels in the form of a wave and can display any color found in the electromagnetic spectrum. Hence, depending on its color, light has different wavelengths and intensities. The light we are able to perceive is known as visible light.
The fundamentals of light
Electromagnetic (EM) radiation consist of particles called photons, which are colloquially known as “small packets of light”. The main quantifiable properties of EM radiation, or light, are the wavelength, intensity and photon energy. The wavelength is used to determine the type of wave involved. Whereas the intensity of light is related to the amount of photons present, which essentially “concentrates” energy. Therefore, greater amounts of photons in light results in greater energy/frequency.
The speed of light
Light has a speed of 299 792 458 m/s (metres per second) in a vacuum. This is incredibly fast and has been the subject of many theories in physics – such as the ability to travel faster than light. However, due to the vastness of outer space the speed of light is still relatively slow in space, as it takes approximately 7 minutes for light from the sun to reach our planet.
The different types of electromagnetic waves
There are several types of electromagnetic waves as mentioned in our JC Physics tuition classes, in terms of the electromagnetic spectrum, each having different properties. The types of EM waves and their applications are:
– Radio Waves: These include some of the longest wavelengths in the EM spectrum, and can have lengths that spread over kilometers. Radio waves are used in communications systems to transmit data. For example, cellular networks use radio waves to allow us to browse the internet on our cellular phones.
– Microwaves: Microwaves are much shorter than radio waves, and are measured in centimeters. Microwaves are typically used in some radar technology and to cook food.
– Infrared: These are closer to visible light, and are used in appliances such as your television. Your TV remote uses infrared light, which can best be seen when attempting to record it through a camera.
– Visible light: These waves can be perceived by the human eye, such as the light emitting from a light bulb.
– Ultraviolet: These waves are shorter than visible light, and are quite powerful. The sun’s rays of light is an example of ultraviolet radiation.
– X-rays: These waves are very short, and are used to penetrate skin to visualize bone in the field of medicine.
– Gamma rays: These are the shortest rays in the EM spectrum and consist of enormous amounts of energy. They are mostly used in chemotherapy to treat cancer.