What Is Light ? Flashcards
Light is…
An electromagnetic wave
More explanation…
A wave that has both electric and magnetic aspects to it. It does not require a medium and travels at the speed of light!
Photon
A packet of light that travels which carries energy and behaves like a wave
White light
Consists of many different photons with different energy levels. The higher the energy the more penetrating something is and the less it’s deflected when it shifts from one medium to another.
A psychological concept that our brain creates when all three of our colour receptors red, green and blue fire off at the same at the exact same frequencies.
When white light passes through a prism…
it BREAKS UP into the SPECTRUM
THE VISIBLE SPECTRUM, high energy
Short wavelength
THE VISIBLE SPECTRUM, low energy
Long wavelength
THE ELECTROMAGNETIC SPECTRUM:
Low energy, long wavelength
Radio waves
Cellphones, radios, tv signals
Microwaves
Energy absorbed by water
Infra-red light
(Think heat) warms food and remote controls
Visible light
Red, orange, yellow, green, blue, indigo, violet
UV (ultraviolet) light
Can cause skin cancer, tans skin, and burns it, can kill microorganisms
X-Rays
Highly pre grating radiation; can be used kill cancer
Gamma rays
High energy, cancer treatment
Properties of light
- Doesn’t require a medium ( it is therefore capable of travelling through a vacuum)
- Light travels at a very high speed ( speed of light in vacuum) (300 million m/s)
- Lost travels in straight lines
- It has wave like properties
- Light it is transferred through radiation
Sources of light: incandescence
Production of light as a result of high temperature like stove
Electric discharge
The process of producing light by passing an electric current through a gas like lightning
Phosphorescence
Light emission due to the absorption of UV light followed by the release of light in the visible spectrum over an extended period of time. Like glow in the dark toys.
Fluorescence
Immediate emission of visible light as a result of the absorption of UV light like fluorescent highlighters
Chemiluminescence
Production of light as a result of a chemical reaction but with little or no heat released like glow sticks
Bioluminescence
Production of light in living organisms, with little or no heat being released. Like bugs maybe fireflies
Triboluminescence
Production of light from friction between certain crystals like when rubbing cave crystals together and making light
