Light Science for Kids
Light science is the study of light and how it behaves. Life on Earth could not exist without light. It is a source of energy, streaming out from a source in tiny little particles, and it also moves in waves. Because light is all around us, it can be easy to overlook it when studying science. But light can surprise you with the different ways it moves and behaves.
Light is radiant energy made up of electromagnetic waves, kind of like radio waves. The eye can see colors of light because of the special frequency of the electromagnetic waves, the way the waves vibrate. Light starts inside atoms, which absorb energy. When atoms absorb energy, the electrons inside the atoms begin moving around. This wild movement of the electrons causes the atoms to release the extra energy. This release of energy goes out from the atom in packets of light.
Light follows laws, so you can learn how light will behave. One law of light is that light always travels in a straight line. Light also moves extremely fast: 186,000 miles per second. Light that starts at the sun takes 8.5 minutes to travel down to Earth where people can see it. Light from the other nearest stars takes more than four years to reach the Earth because those stars are so far away. A light year describes the distance that light waves can travel in one year.
Optics is the study or science of light, which includes learning about how light behaves in different situations. Knowing that light will always take the fastest route between two objects makes it possible to control light in some cases. For example, you can control light and make shadows by blocking the straight line of light with an object that light won't pass through: Shining a flashlight onto the ground and placing a book between the beam of light and the ground will create a shadow.
The properties of light include its intensity or strength, direction, and the frequency of the wavelengths. Several different types of light exist. Visible light is the light that the human eye can see. Some animals can see types of light that humans cannot see, light traveling on different wavelengths. For example, some insects can see ultraviolet rays of light. Ultraviolet rays come from the sun, and they are invisible to humans. Infrared light has wavelengths that are too long for the human eye to see. Photons are the tiny little particles that make up waves of light. Because photons have no mass, they can travel very fast. Photons are special because they can behave as both particles and waves to make light visible.
Without light, you would not be able to see anything. It's possible to see objects because light waves bounce off of objects and hit the eye. From there, the eyes send signals to the brain, and the brain figures out what the eyes are seeing. This process happens instantaneously, so quickly you don't even realize it. Without light, life could not exist on Earth. Sunlight warms the planet to make it the right temperature for humans, animals, and plants to live. Sunlight also provides the energy that plants need to make their food, a process known as photosynthesis. Without photosynthesis, there wouldn't be food on Earth.
Water can bend light waves, which is known as refraction. This happens because light waves travel more slowly through water than they travel through air. Rainbows are an excellent example of refraction. When rain falls while the sun is shining, the water droplets refract the sunlight because water has a different density than air. The light waves refract and bend inside the water droplet, and then they change direction again once they come out of the water. Colors in a rainbow happen because the droplets refract light at different angles.
Objects have to reflect light for the eye to see them. Reflection happens when an incoming light wave shines at a surface and bounces back off again. If you shine a light at a polished surface like a mirror, the light beam bounces back as it reflects. If a surface isn't smooth and shiny, light will still reflect, but it will be scattered instead of all bouncing straight back. This is known as diffused reflection. Laws of reflection control how light reflects off of surfaces. Reflection also determines how the eye sees colors. Some light is absorbed by different-colored objects and some light reflects back. The colors you see depend on which colors reflect back to your eyes. To see the color red, an object would absorb all but the red light, and this color would bounce back to the eyes. Visible light is also called white light. White contains all of the colors of light. The three primary colors of light are red, green, and blue. Primary colors can overlap to make secondary colors, such as pink and purple.
Objects that don't allow light to pass through are called opaque. Opaque objects create a dark area that interrupts the path of light waves. A person's body is an example of an opaque object, which is why people have shadows when they are outdoors in the sun. The size, shape, and position of an opaque object will determine how a shadow looks. Shadows can move if the source of light moves or if the object moves.
Prisms are transparent, geometric figures that can redirect light. Prisms are usually made out of glass or clear plastic, and they have angles such as triangular or hexagonal shapes. The angles of a prism separate white light to create colors by bending them. Bending the wavelengths of light differently creates different colors. To create the violet color, wavelengths of light have the most refraction. To create the red color, wavelengths of light have the least refraction.
Shine light on scientific facts so you can understand how everything revolves around light. The eyes see objects and the brain perceives objects because of light. Activities and experiments can help you see how light behaves after you learn about this type of energy. It's possible to see how light travels, bends, and reflects to see amazing colors.