Electromagnetic waves do not depend on a medium, but can use one. There are 6 types of electromagnetic waves: radio waves (including microwaves infrared waves visible light ultra violet waves X-rays gamma rays
Electromagnetic energy comes in different forms because of the varying wavelengths of each wave. Some of these waves we can see, some we can feel, and others can be extremely harmful. Below is a chart of electromagnetic energy and its various forms.
Sources of Light Chemiluminescent (light energy released by chemical reactions)glow sticks Chemiluminescence Movies (Shackwave/Flash) firefly light Bioluminescence (light produced by living organisms) Phosphorescent (light energy is stored and released later as visible light)paint Wood ( fire ) Ultraviolet light ---? Energy absorbed ---? Visible light energy by particles energy Florescent (ultraviolet light is absorbed by fabric particles, which in turn emit some of the energy as light - glowing) Candles or Oil Lamps Electrical energy ---? Thermal energy ---? Visible light energy Incandescent (heat causing a filament of metal to glow - visible light) Sun Artificial Light Sources Natural Light Sources
Only electromagnetic waves can travel through space, because space is a vacuum. Light is an electromagnetic wave. Sunlight can travel to the earth through the vacuum of space (no medium) , and light can also travel through the air (a medium ) across the room.
Visible light waves make up the rainbow, which is only a small part of the electromagnetic spectrum. The electromagnetic spectrum includes "light" with wavelengths far too long for us to see
Examples from other parts of the Electromagnetic spectrum include: Radio waves: infrared waves: visible light ultra violet waves: X-rays: gamma rays:
When light strikes any form of matter, One of 3 things can happen: it can be reflected, absorbed, or transmitted.
Reflection happens when light bounces off an object. Absorption is the transfer of light energy to matter. Transmission is the passing of light through matter.
Transparent matter is matter though which light is easily transmitted. Glass is transparent.
Translucent matter transmits light but also scatters it. Frosted windows are translucent.
Opaque matter does not transmit any light. Computers and books are opaque.
Luminous: a light source Illuminated: light is shining on an object Bio-luminous: living thing that produces light (like a fire fly)