chapter 11 - waves 1 Flashcards
what is a progressive wave?
an oscillation that can travel through matter, transfer energy from one place to another but not matter
what is a transverse wave?
oscillations are perpendicular to the direction of energy transfer
what is a longitudinal wave?
oscillations are parallel to the direction of energy transfer
what is the wave equation?
wave speed= wave length x frequency
or
wave speed= wavelength/ time
define the displacement?
distance from the equilibrium position in a particular direction
define amplitude?
maximum displacement from equilibrium position
define frequency?
number of wavelengths passing a given point per unit time
define wavelength?
minimum distance between two points in phase on adjacent waves
define wave speed?
distance travelled by wave per unit time
what is the phase difference?
the difference between the displacements of particles on different waves. measured in radians
what is the phase difference of an in phase wave?
phase difference of 0
what is phase difference of an out of phase wave?
phase difference of pi
how can you determine frequency using an oscilloscope
each horizontal square on oscilloscope represents a time interval. this is called time base. each vertical square = p.d from the microphone picking up wave. using the time we can use formula F=1/T
define the reflection of a wave?
wave changes direction at a boundary between two different media, remaining in the original medium.
state the law of reflection
angle of incidence = angle of reflection
what occurs to the frequency and wavelength of a wave that is reflected?
they remain the same
define the refraction of a wave?
when a wave changes direction as it changes speed from one medium to another
what is partial reflection?
when a wave refracts some is reflected
what occurs to the wavelength and frequency of wave when it refracts?
frequency remains the same however wavelength changes. v= frequency x wavelength
define diffraction?
when a wave passes through a gap or travel around an obstacle they spread out.
what affects diffraction?
the size of the wavelength compared to the size of the gap
define polarisation?
particles oscillate along only one direction, wave is confined to only one plane.
define the intensity of wave?
radiant power passing through a surface per unit area
formula for intensity
I = P/A or P/ 4 X pi X r^2
what is the relationship between intensity and amplitude
intensity is proportional to the amplitude^2
what are properties of an electromagnetic waves?
they are waves that travel at speed of light in vacuum
can be plane polarised
