Chapter 11 Waves 1 Flashcards
What is a progressive wave?
It is a wave that moves through matter or a vacuum and It transfers energy without transferring matter.
What is a transverse wave?
It is a wave that oscillates perpendicular to the direction of travel of the wave.
What are some examples of transverse waves?(4)
Waves on the surface of water Any electromagnetic wave Waves on a stretched string Swaves produced by earthquakes
What is a peak and what is a trough?
These are both the maximum displacement of a particle from equilibrium. Peak is the positive displacement and a trough is the negative displacement
What is a longitudinal wave?
It is a wave that oscillates parallel to the direction that the waves travel
What are some examples of longitudinal waves?(2)
Sound pwaves from earthquakes
What is displacement?
It is the distance that a particle is from equilibirum
What is amplitude?
It is the maximum displacement from equilibrium
What is wavelength?
This is the minimum distance between two identical points on a wave
What is the period of oscillation?
This is the time it takes for one oscillation
What is the frequency?
It is the number of wavelengths passing a point in a second, also the number of oscillations per second
What is wave speed?
It is the distance travelled by a wave per unit of time
What is the wave equation?
V = Fλ
What is the equation to find frequency from time period?
f = 1/t f = frequency t = timeperiod
What is the law of reflection?
The angle of incidence is equal to the angle of reflection
What is refraction?
This is when light changes the medium it flows through and due to the change in speed it changes direction
What happens if the speed of the wave slows down when changing medium?
Refract towards the normal
What happens if the speed of the wave increases when changing medium?
It refracts away from the normal
What happens if a) light or b) sound enters a denser medium?
a) When light enters a denser medium it slows down b) when sound enters a denser medium it speeds up
What happens when light enters water from air?
It bends towards the normal and the wavelength gets smaller
What is diffraction and what is the property unique to?
Diffraction is unique to waves and is when it spreads out as it passes through a gap
What is polarisation? and plane polarisation?
This is when particles oscillate in a single direction. along a single plane
What does unpolarised light look like?
It is light that oscillates in multiple directions.
What does the amount of diffraction rely on?
It relies on the size of the gap that it passes through and the wavelength
What does partial polarisation? and when does it happen?
This is when light oscillates in more than one plane but it not fully unpolarised. its sort of half way between This happens when light reflects off a surface like a lake
What is intensity and what is its equation and units?
It is the radiant power passing through a surface per unit of area. I = P / A Units: Wm^-2
What happens to the intensity if the distance from a source doubles?what is the general equation
The intensity is 1/4 I ∝ 1/r^2
How is amplitude and intensity related?
Intensity ∝ (amplitude)^2
What is special about electromagnetic waves vs other waves?
It does not need a medium to pass through
What is the wave equation for electromagnetic waves?
c = fλ
What is the speed of light? and symbol?
c = 3x10^8
What is a polarising filter and how does it work?
It is a filter that polarises light. It acts like a gate and so only the light that is oscillating with the direction of the rails is allowed through. Light that oscillated differently is simply cut out
What is a use for polarising filters and explain how this is usefull?
It is used for ariels where the wave is polarised to reduce interference between different transmitters.
