MOD 5 LECTURE 1                            CHARACTERISTICS OF WAVES

In this lecture you will:

CHARACTERISTICS OF ALL WAVES: WATER, SOUND, EMS 
    WAVES ARE PURE ENERGY !
Waves travel in straight lines when not interacting with matter !
FORMULA IS:  V = lambda x W

OR, velocity = wave length x frequency

1. wave length is the distance from one crest to the next crest
 ..... is called > lambda
2. frequency is the # of crests go by a given point per second.. A.K.A. Hz
..... is labeled > W
3.  velocity is speed and direction of wave = V

..... for light, v = speed of light (c)
..... for sound v = 775 miles per hour (at 75oF)


http://en.wikipedia.org/wiki/Wave_propagation
4.  amplitude is height of wave 

 
V = LAMBDA X W:
1. Velocity for waves of the EMS are CONSTANT  at the SPEED OF LIGHT SOL in a vacuum (ONLY EMS, not true for sound and water)

2. Because the velocity is constant, then as the frequency increases the wave length MUST decrease, that is, they are inversely proportional

EXAMPLE: 
100 = 5 x 20
100 = 4 x 25
100 = 2 x 50
100 = 1 x 100

SO: 
UV has SHORT wave length but HIGH frequency waves

Radio waves have LONG wave length, but LOW frequency waves

RADIO WAVES ARE WAVES OF THE EMS, NOT SOUND


 
COMPARISON OF EMS, SOUND AND WATER WAVES
WAVES NEEDS MATTER TO PROPAGATE SPEED
WATER YES, it is the energy wave that moves forward not the water itself which mostly goes up and down as the energy moves thru it.  "A tsunami can travel at well over 970 kmh (600 mph) in the open ocean - as fast as a jet flies. It can take only a few hours for a tsunami to travel across an entire ocean. A regular wave (generated by the wind) travels at up to about 90 km/hr."
http://www.enchantedlearning.com/subjects/tsunami/
600 mph

970 kmh 

SOUND YES, the molecules in air, water and solids transmit the energy "This equates to 1,236 kmh (768 mph) or about one mile in five seconds." 
http://en.wikipedia.org/wiki/Speed_of_sound
768 mph

1,236 kmh

EMS NO, waves of the EMS moves thru space/vacuum altho it can interact with matter (see later lectures)  "...... roughly a million times faster than sound, and fast enough to circle the Earth more than 7 times in one second." IN SPACE ONLY, matter slows EMS down 
http://en.wikipedia.org/wiki/Speed_of_light
670,616,628.6 mph

1,079,252,848.8 kmh