Light Light An Electromagnetic Wave Light is a

Light

Light – An Electromagnetic Wave • Light is a “wave”. • Light is special because light can travel through vacuum of outer space.

Light – An Electromagnetic wave • An electromagnetic wave: is a wave that has both electric and magnetic parts, does not require a medium, and travels at the speed of light

Electromagnetic spectrum • The term “Light” usually refers to the visible part of the electromagnetic spectrum. Video – Electromagnetic Spectrum

Wavelength and Frequency • Wavelength – the distance between successive crests on a wave. • Frequency – the number of cycles a wave goes through in one second.

More on the EM Spectrum Longer Wavelength (Low Energy) Shorter Wavelength (High Energy)

White Visible Light • Continuous sequence of colors. Color sequence is called the visible spectrum Red Orange Yellow Green Blue Indigo Violet ROY-G-BIV

The Production of Light Incandescence – Hot things glow

The Production of Light Electric discharge – Electric current passing through a gas

The Production of Light Bioluminescence – Chemiluminescence in living organisms

The Production of Light Phosphorescence and Fluorescence - Material absorbing U. V light In phosphorescence, visible light is emitted over a period of time In fluorescence, immediately Phosphorescent powder under visible light, ultraviolet light, and total darkness

The Production of Light Phosphorescent powder under visible light, ultraviolet light, and total darkness. – Triboluminescence - friction from scratching, crushing, or rubbing certain crystals

The Production of Light – Light-Emitting Diode (LED) • Electric current flowing in semiconductors