We see light from the sun every day. Light is measured in ‘waves’ and the light that we can see is only a small portion of the types of light. They are measured in the ‘electromagnetic spectrum’. The human eye sees specific areas of the spectrum, but other animals and insects can actually see parts of the spectrum that we can’t.
Light is an energy beam that moves in wavelengths. It is made up of tiny photons, each contains a lot of energy. The strength of the light depends upon the amount of energy each photon contains.
- A light wave is made up of energy in the form of magnetic and electric fields. These fields have a right angle vibration to the wave direction of movement and at right angles to each other.
- Light will travel in a completely straight line until it hits an object that will bend it. The light that is in a straight line are called ‘light waves’.
- The study of the behavior and properties of light is known as ‘optics’. This is a scientific branch of physics.
- Light travels in a vacuum at 300,000 km per second (186,000 miles per second).
- Space does not have any light. We can see things in space due to light bouncing off of the objects in space.
Light doesn’t travel as fast when it has to pass through mediums that are different, such as air, water or glass. These mediums cause the light to ‘refract’ and that slows the light down. The refractive index of glass is 1.5, slowing the speed of light down to 200,000 km per second (124,000 miles per second). Water has a refractive index of 1.3 and the refractive index of air is 1.0003. Air slows light down only a small amount.
Isaac Newton studied light as it hit a glass prism. When he saw the light expand into the different colors (ROYGBIV): red, orange, yellow, blue, indigo, violet, he realized that light refracts and each color traveled through glass (or other materials) at varying speeds. We can see the same thing happen when we see light through a prism or even when we see a rainbow. Each color within light has a different wave length.
Each type of light has a varying length of ‘wave’. Some animals can see ultraviolet light (UV) but the wavelength is not available for the human eye to see. Scientists have developed technology so that we can view UV light.
- Infrared light has a wavelength that is too long for the human eye as well.
- The speed of light is incredible. For light to get from the earth to the moon it takes only 1.255 seconds.
- Light that we see from the sun actually left the sun ten minutes before we see it.
- Sunlight is pretty powerful. Light from the sun can reach 262 feet (80 meters) in the ocean.
Galileo Galilei was an Italian scientist that developed a number of scientific discoveries. One of them was the creation of a telescope that was thirty times the magnification of other telescopes. He used his telescope to look at many of the planets and discovered four of the largest moons that were orbiting around Jupiter. These four moons were called ‘Galilean satellites’.
Light can be controlled and produced in so many ways. A camera can control the amount of light that comes into the camera lens. We also use light in televisions, medical systems, copy machines, telescopes and satellites.
Light is used by plants to convert the light into energy as their ‘food’. The process is called ‘photosynthesis’ and converts carbon dioxide through the energy of the light.