15.2
Electromagnetic waves need no medium, are produced by moving electrons in a field.
Can be reflected, refracted, diffracted, produce standing waves
Tiny bundles of energy that produce light.
They increase as frequency increases and wavelengths decrease
Sound and Light
4
Absorbs Energy
Light is the fastest wave in the universe
Speed of light is 300 million m/sec- it takes 8 minutes from sun to earth
Affected by the material that it passes through
Transparent- air, water, glass Translucent- frosted glass diffuses light
Opaque-light can’t pass through.
If light travels through an object it is =transparent
If light is blocked by an object and a dark shadow is cast it is= opaque.
If some light passes through but not all and a light shadow is present it is=translucent.
*AIMS:Primarily Physics: Just Passing Through Activity
Quantity of amount of light illuminating a surface, dependant on amount of light.
Decreases with distance
Sound and Light
10
Describes physical waves using amplitude, wavelength and frequency.
Arranged by Frequency and wavelength
Left side of spectrum has low frequency and large wavelengths, right side has high frequency and close wavelengths
You begin with radio wave, microwaves, infrared, visible light, ultraviolet, x-rays and gamma
Radio- lowest frequency, longest wavelength. Includes AM/FM and radar
Radar- Radio Detecting and Ranging
Radar uses short radio impulses to locate and monitor speed once the signal is reflected back.
Microwaves follow radio waves and are used in cooking/communication
Infrared- slightly lower wavelength than visible light
Felt has heat like in the sun and warming lamps
Visible light – color spectrum
ROY G BIV Red, orange, yellow, green, blue, indigo ,violet
The colors are ordered by wavelength.
50% of the sun’s light is visible
Ultraviolet- higher frequency than visible light
Kills bacteria, causes cancer, produces vitamin D
X-rays- frequency above ultraviolet waves, passes trough skin but is absorbed by bone, Lead can absorb all X-rays
Gamma rays- has highest frequency and shortest wavelength, has highest energy and can penetrate 3 meters of concrete.