4.4 - Wave Properties 2 + the tests Flashcards
what is the superposition effect
when waves meet they pass through eachoher
however they combine for an instant before they move apart which is called superposition
what is the principle of superposition
when two waves meet the total displacement at a point is equal to the sum of the individual displacements at that point
what happens when a crest meets a crest
they create a super as they reinforce eachother
what happens when a trough meets a trough
a super trough is created and they reinforce eachother
what happens when a crest meets a trough at the same amplitude
the resultant displacement is zero and the waves cancel eachother out
what happens when they meet and ones a trough and ones a crest but they aren’t the same amplitude
the resultant force is called a minimum
what happens at the nodes where progressive waves meet
they form points of no displacement as the two sets of waves are always 180 degrees out of phase so they therefore cancel eachother out
how can 2 vibrates on water show superposition
points of cancelation are created when a crest from one dipper meets a trough from the other dipper ( these points are shown by the gaps in the wavefronts)
points of reinforcement are created where the crest from one dipper meets another crest from another or where a trough meets a trough (theses are shown when the wavefronts meet)
what is interference
because waves are continuously passing through eachither at a constant frequency and a constant phase difference the cancellation or reinforcement occurs at fixed positions
where do coherent sources produce an interference pattern
where they overlap because they vibrate at the same frequency with a constant phase difference
what would happen to the interference pattern if the phase difference changed at random
the points of cancellation and reinforcement would move about at random and no interference pattern would be seen
what can a microwave transmitter and receiver be used to demonstrate
reflection , refraction , diffraction , interference , and polarisation of microwaves
how would you set up the tests for microwaves
the transmitter produces microwaves of a wavelength of 3cm
the receiver (diode detector) can be connected to a suitable meter which can measure the intensity of the microwaves at the receiver
how to show that the microwaves that the microwaves become weaker as they weaker as they travel away from the transmitter
move the receiver gradually away from the transmitter and note that the receiver signal decreases with distance from the transmitter
what should you do to prove the waves can’t go through metal
place a metal sheet between the transmitter and receiver
