waves Flashcards
order of wave spectrum
-radio waves
-microwaves
-infra red
-visible light
-ultra violet
-x-ray
-gamma rays
why do objects appear opaque?
they don’t transmit any light
define intensity:
power of radiation per unit of area
objects that are hotter than their surroundings emit _____ radiation than they absorb
more
what type of wave is a sound wave?
longitudinal
what is ultrasound?
sounds above 20,000 Hz
how are ultrasound used to view internal structures?
-ultrasounds are refracted, some are also reflected at boundaries
-when it is fired at an object, every time it hits a boundary some of the waves are reflected back at us
-if we know the time taken and speed for it to travel, we can work out the distance of these boundaries and produce images
properties of p waves:
-longitudinal
-can travel through liquids and solids
-faster than s waves
properties of s waves:
-transverse
-only through solids
define a transverse wave?
The movement of the particles is at right angles to the direction of the wave.
define a longitudinal wave?
movement of the particles is parallel to the direction of the wave.
Name a transverse wave
Light, water, mexican wave, all the waves on the electromagnetic spectrum, s-waves
longitudinal wave, what is meant by an area of compression, and an area of rarefaction?
compression is where the particles are closest together, rarefaction is where the particles are furthest apart
the amplitude of a wave
maximum displacement of the wave away from its undisturbed position
What is frequency?
Frequency is the number of waves that pass a point per second
period of a wave?
period is the time (number of seconds) it takes for each wave to go by
What is rarefraction?
As light moves from a less dense medium to a more dense medium the light bends towards the normal and vice versa
what can UV radiation cause to the skin?
sunburn, prolonged exposure can cause skin cancer
what waves are used for communication?
radio waves, microwaves, infra red, visible light
what is a wave speed?
speed at which the wave moves or energy is passed through a medium
how do waves transfer through a solid?
particles vibrate against each other and transfer kinetic energy through the material
technique used to detect objects in deep water and measure water depth:
-echo sounding
-high frequency waves emitted, reflected and detected
-time diff betw emission and detection and wave speed used to calc distance
what do waves do
transfer energy from one place to another (w/o transfer of matter)
long waves travel by
diffracting around the curved surface of earth
