Waves Flashcards
what is a progressive wave
carries energy from one place to another without transferring any material. its caused by something vibrating the particles near the source.
what is a transverse wave and examples
Oscillations of particles are perpendicular to direction of energy transfer
-electromagnetic waves/water waves/ s-waves
what is a longitudinal wave and examples
oscillations of particles are parallel to direction of energy transfer
-sound waves/ p-waves
what is it does mean when light is polarised
the particles in the wave are oscillating in more than one plane
what type of wave can be polarised
transverse
how do you polarise light
by using a polarising filter, a square with small openings along through it which prevents light oscillating in more than one plane
what happens when 2 filters 90 degrees apart are put in front of light
no light gets through
what happens when 2 filters 45 degrees apart are put in front of light
the light doesn’t get through as much making it look darker
what are uses of polarised light
tv antennas- light is sent polarised which is why they need to be in a certain position to be reserved
sunglasses- they are coated with polarising filter so some of the light is blocked
what are some natural polarisers
water/glass/tarmac
went light hits them the light reflected off is partially polarised making them easier to be polarised with a filter
what is the wave speed experiment (microphones)
two microphones connected to a computer are put at a fixed distance apart. the computer records when the first microphone hears it then the second.
this gives you a distance and a time
what is the wave speed experiment (echo)
someone makes aloud noise at a fixed distance to a wall. then measure the time to hear the echo again. make sure to double the distance.
what is the wave speed experiment (gunshot)
have someone with a starter pistol and a great distance with a stop watch. start the timer when you see the flash and stop it when you hear the gunshot.
what is superposition
when two or more waves combine together
what are the three types of superposition
constructive interference- pulses combine
destructive interference- pulses partially cancel out
total destructive interference- pulses cancel out
what are the conditions for producing a stationary wave
-it is the superposition of two progressive waves travelling in opposite direction
-they have the same frequency and wavelength
-similar amplitude
what is a stationary wave
a wave where no energy is transferred. you can have both longitudinal and transverse stationary waves
what are nodes and anti-nodes
nodes-points of no displacement, total destructive interference is always occurring here
anti-nodes- points of maximum displacement, constructive interference is happening here
what are the distances between 2 nodes and 2 antinodes
they are both half a wavelength apart from each other
what are examples of stationary waves in real life
strings on guitars and pianos are transverse stationary waves
wind instruments are longitudinal stationary waves
how are microwaves an example of how stationary waves work
an easy way for a stationary wave to be formed is to reflect back on itself
in a microwave the food has to spin or the food doesn’t cook at the nodes
what are harmonics
the certain frequencies where stationary waves can form. this is when there is a whole number of wavelengths.
what is the fundamental frequency
the Lowest frequency that a harmonic can be, only fitting 1/2 a wavelength
how can you create the fundamental frequency
use a signal generator to vibrate a string up and down, the string will reflect back on itself due to a moveable bridge and pulley with masses of the end.