Booklet 11: Waves Flashcards
Progressive Waves
waves that move through a material or a vacuum and transfer energy from one position to another
Amplitude
the maximum displacement of any point on the wave from its undisturbed position (equilibrium)
Wavelength
the distance from any point on a wave to the next exactly similar point
Period
the time taken from one complete oscillation of a point in a wave
Frequency
the number of oscillations per unit time of a point on a wave
Mechanical Waves
waves that need a substance (medium) through which to travel
eg. sound, strings, water, seismic
Longitudinal Waves
the particles of the medium vibrate parallel to the direction of the wave velocity
Transverse Waves
the particles of the medium vibrate at right angles to the direction of the wave velocity
Phase Difference
the amount by which one oscillation leads or lags behind another (degrees or radians)
Intensity
the rate of energy transmitted per unit area at right angles to the wave velocity
I ∝ 1/(r^2) [radius]
Intensity and Amplitude
intensity ∝ amplitude^2
I ∝ A^2
intensity/amplitude^2 = constant
Wave Equation (speed)
v=λ/T
wave speed = wavelength / period (s)
:
v=(1/T)*λ and f=1/T
therefore
v=fλ
Polarisation
(TRANSVERSE ONLY) the process by which oscillations are made to occur in one plane only
Refraction
when waves change direction and speed as they move from one medium to another. the wavelength changes, the frequency does not
Refractive Index
the higher the refractive index, the slower the e.m. radiation travels through this material compared with its speed in a vacuum
n=c/v
n = speed of light in a vacuum / speed of light in the material
