Stationary Waves Flashcards
Stationary wave occur when
Stationary waves are formed when two progressive waves with the same frequency (and
ideally the same amplitude), travelling in opposite directions, superpose.
Where does maximum amplitude occurs at in a stationary wave
At its antinode
Where does minimum amplitude occurs at in a stationary wave
At its node
The frequency of a stationary wave is the same at …
all points,
except for the node where it is 0.
The phase difference between two points on the wave is given
by…
180°n, where n is the number of nodes between the two points.
How do stationary wave differ from progressive waves in terms of energy?
Stationary waves do not transfer energy, they store it.
To investigate a technique on how to produce stationary waves in a stretched string
To produce a stationary wave in a stretched string, the string is held taught over a pulley. A vibration generator is used to oscillate the string in a coherent manner, with the frequency being adjusted until a stationary wave is produced. The initial wave produced is reflected at the pulley and, producing two waves with the same frequency, travelling in opposite directions, which superpose to make a stationary wave. The transmitter and pulley ends will be nodes, with a node-antinode pattern along the string.
To investigate a technique on how to produce stationary waves with microwaves
To produce a stationary wave with microwaves, a microwave transmitter can be used to
produce a wave, which is reflected off a metal plate. The incident and reflected waves superpose
to make a stationary wave. A microwave receiver can be moved between the transmitter and the
plate and will observe a minima, maxima pattern.
To investigate a technique on how to produce stationary waves with sound in an air filled tube
Stationary waves can be produced with sound in an air filled tube. A tuning fork is used to
produce a loud sound, and is then held over the end of the tube. The length of the tube can be
adjusted (e.g. by placing one end in water) until a stationary wave is produced. The stationary
wave formed will vary depending on the air column – if the column is open at both ends, then
there will be an antinode at each end, but if the column is open at one end only, then the open
end will have an antinode, and the closed end will have a node.
The number of nodes produced in the stationary wave depends on the …
frequency of the
vibration.
The fundamental frequency of a stationary wave is the ….
lowest frequency of
vibration for a given arrangement.
If the fundamental frequency was 3Hz, and a student increases the frequency of a string attached to a pulley to 5Hz, explain why a stationary wave will not be formed?
Because at frequencies other than multiples of the fundamental frequency, stationary waves will not be formed. 5 is not a multiple of 3.
What’s the wavelength of a stationary wave when it oscillate at the fundamental frequency
length=lambda/2
because half a wavelength is shown in the string
What’s the wavelength of a stationary wave when it oscillate at the nth harmonic
length=n x lambda/2
because half a wavelength is shown in the string
formula for the fundamental frequency is
f =1/(2l) x sqrt(T/mui)
where mui is kg per m
l is the length of the string
and T is the tension in the string
