Waves Flashcards
What is a transverse wave
The oscillations are perpendicular to the direction of energy transfer. Particles vibrate. Have peaks and troughs. Example - Em waves
What is a longitudinal wave
Oscillations that are parallel to the direction of energy transfer. Particles vibrate.
What is a progressive wave
An oscillation that travels through a medium, transferring energy from one place to another but not matter.
What is phase difference
The difference in displacement between 2 waves given in degrees or radians, found by displacement/wavelength * 360 or 2pi
Using an oscilloscope to find wave frequency
The time base is the time period given by one square on the screen. f = 1/T
What is reflection and law of reflection
Reflection occurs when a wave changes direction at a boundary between 2 mediums, remaining in the same medium. Angle of incidence to normal is equal to angle of reflection to normal.
What is refraction
When a wave passes into another medium, the speed and direction at which it was previously traveling is altered. If the wave slows down, it refracts towards the normal. If it speeds up, it refracts away from the normal. Always partial reflection when wave is refracted.
What is diffraction
When a wave passes through a gap, it spreads out. If the gap is similar in size to the wavelength, there is a greater degree of defraction.
What is polarisation
When the particles are confined to vibrate in a single plane. Longitudinal waves cannot be polarised as they are already confined to a single plane. A polariser is used to polarise em waves.
What is intensity
The radiant power of a progressive wave passing through a surface per unit area. Intensity is directly proportional to amplitude^2
Wave length of radio waves
10^6 - 10^-1
Wavelenght of microwaves
10^-1 - 10^-3
Wavelength of infrared
10^-3 - 7*10^-7
Wavelength of visible light
700-400 nanometres, 10^-7
Wavelength of ultraviolet
4*10^-7 - 10^-8