Waves Flashcards
E =kA^2
E₁/A₁^2 = E₂/A₂^2
E = Energy (J) A = Amplitude (m)
Travelling wave equation
y = Asin2π(ft - x/λ)
for a wave travelling left to right
y = Asin2π(ft + x/λ)
for a wave travelling right to left
y = displacement (m) x = distance from the origin of the particle (m) f = frequency (Hz) t = time (s) λ = wavelength (m)
Phase Difference
ø = 2π(x/λ)
ø = Phase angle (rad) π = pi x = distance between points on a wave (m) λ = wavelength (m)
Stationary Waves
are formed by the interference of two waves that are REFLECTED the waves have the same frequency and amplitude, travelling in opposite directions. A stationary wave can be described in terms of nodes and antinodes.
The incident and reflected waves interfere.
how do you calculate λ from this travelling wave equation
y = 9.50x10^-4sin(922t-4.50x)
2π has been factored into both the frequency and the wavelength thus
4.50 = 2π/λ
so
λ = 2π/4.50
how do you calculate λ from this travelling wave equation
y = 0.250sin2π (118t - 0.357x)
2π has NOT been factored in this equation.
thus
0.357 = 1/λ
so
λ= 1/0.357
if the frequency of a stationary wave is increased what will happen to the sound?
the sound will get quieter until the frequency has doubled.
if the frequency is doubled then what happens to the wavelength
the wavelength is then halved.
as frequency and wavelength are proportional to each other.