Along with visible light their lies many other waves but we just can't see them. These waves fall into what we call the Electro Magnetic Spectrum. These other waves are; radio waves, microwaves, Infrared Waves, Ultraviolet light, X-Rays and Gamma Rays.
Radio Waves- are vital to communication around the world and are also used to separate models of communication.
Microwaves- are shorter than radio waves, which means they carry more energy Microwaves are mostly used to heat food. Microwaves cause water particles in food to vibrate, heating the food.
Infrared Waves- can't be seen but they are felt as heat. Special equipment can sense infrared radiation and detect hotter and cooler areas. Images of infrared radiation are called Thermo Grams.
Ultra Violet Light-carries more energy than visible light and can burn the skin, increasing the risks of skin cancer. Most of the sun's UV rays are absorbed by Earth's ozone layer but it is still advisable to wear sun block, which provides an opaque layer that prevents UV rays from reaching your skin.
X-Rays and Gamma Rays- both represent extremely high-energy radiation. Both rays penetrate tissue. X-Rays with lower energy have difficulty passing through bone, making them useful for medical imaging. Gamma Rays are used to kill cancer cells.
Artificial Sources of Light
At the centre of an Incandescent bulb there is a filament. When you turn it on, electrical energy flows through the filament, heating it to extremely high temperatures. This causes the filament to glow white hot which is the light that we see.
A fluorescent bulb is a glass tube filled with a small amount of gas. The inside of the bulb is coated with a powder called phosphor. Electricity passes through a fluorescent bulb many times per second. Each time it passes through, it makes the gas emit UV radiation. The UV radiation strikes the phosphor on the inside of the bulb which glows and emits visible white light. The emission of white light in this way is called fluorescing.
Phosphorescence light is slightly different than fluorescent. Some substances have the ability to store energy from the radiation that hits them. And they can emit light for a long time after the source has stopped. This ability is known as phosphorescence. Phosphorescent materials are often used in novelty items.
When Light Gets Inside
In order to see, light rays must strike the sensitive retina at the back of the eye. The retina is a special layer that is filled with photoreceptors, cells that are sensitive to light. There are two types of photoreceptors. Rods are highly sensitive to light they can function in low light. Cones can't function in low light so all you see are shades of grey. This is similar to black and white film on cameras. When light strikes the retina, photoreceptors are stimulated, and they send...