CHAPTER 11 Flashcards
P- WAVES
primary waves- longitudinal waves that travel through the earth from an earthquake
S- WAVES
secondary waves- transverse waves that travel through the earth from an earthquake
PROGRESSIVE WAVE
a wave where the peaks and troughs, or commissions and rarefactions, move through the medium as energy is transferred
LONGITUDINAL WAVE
a wave where the medium is displaced in the same line as the direction of energy transfer- oscillations are parallel to the direction of wave travel
TRANSVERSE WAVE
a wave where the medium is displayed perpendicular to the to the direction of energy transfer- the oscillations of medium particles are perpendicular to the direction of wave travel
EQUILIBRIUM POSITION (WAVES)
the resting position for particles in the medium
RESTORING FORCE
a force that tries to return a system to its equilibrium position
PEAK
the maximum positive amplitude of a transverse wave
TROUGH
the maximum negative amplitude of a transverse wave
COMPRESSONS
a moving region in which the medium is denser or has higher pressure than the surrounding medium
RAREFACTIONS
a moving region in which the medium is less dense or has less pressure than the surrounding medium
DISPLACEMENT (WAVES)
the distance from the equilibrium position in a particular direction
AMPLITUDE
the maximum displacement from the equilibrium position
WAVELENGTH
minimum distance between two points in phase on adjacent waves
PERIOD OF OSCILLATION
the time taken for one oscillation or time taken for wave to move one whole wavelength past a given point
FREQUENCY
the number of wavelengths passing a given point per unit time
WAVE SPEED
the distance travelled by the wave per unit time
WAVE PROFILE
a graph showing the displacement of the particles in the wave against the distance along the wave
IN PHASE
particles oscillating perfectly in time with each other are in phase
ANTIPHASE
particles oscillating completely out of step with each other are in antiphase
REFLECTION
the change in direction of a wave at a boundary between two different media, so that the wave remains in the original medium
LAW OF REFLECTION
the angle of incidence is equal to the angle of reflection
ANGLE OF INCIDENCE
the angle between the direction of travel of an incident wave and the normal at a boundary between two media
ANGLE OF REFLECTION
the angle between the direction of travel of a reflected wave and the normal at a boundary between two media
WAVEFRONT
a line of points in phase with each other i a wave, perpendicular to the direction of energy transfer
REFRACTION
the change in direction of a wave as it changes speed when it passes from one medium to another
POLARISATION
the phenomenon in which oscillations of a transverse wave are limited to one plane
PLANE POLARISED
description of a transverse wave in which oscillations are limited to only one plane
UNPOLARISED
description of a transverse wave in which oscillations occur in may planes
PARTIALLY POLARISED
description of a transverse wave in which there are more oscillations in one particular plane, but the wave is not completely plane polarised- occurs when transverse waves reflect off a surface
INTENSITY
the radiant power passing through a surface per unit area
ELECTROMAGNETIC WAVE
transverse waves with oscillating electric and magnetic field components, such as light and X-rays
ELECTROMAGNETIC SPECTRUM
the full range of frequencies of electromagnetic waves, from gamma to rays to radio waves
RADIO WAVES
long- wavelength electromagnetic waves, with wavelengths greater than 10^-1
GAMMA WAVES
short- wavelength electromagnetic waves, with wavelengths from 10^-10 to 10^-16
X-RAYS
short wavelength electromagnetic waves, with wavelengths from 10^-8 to 10^-13, which can be used in medical imaging
REFRACTIVE INDEX
the refractive index of a material n=c/v
TOTAL INTERNAL REFLECTION
the reflection of all light hitting a boundary between two media back into the original medium when the light is travelling through the medium with the higher refractive index and the incidence angle at the boundary is greater than the critical angle
CRITICAL ANGLE
the angle of incidence at the boundary between two media that will produce an angle of refraction of 90 degrees