Physics – Formulae Sheet
14. WAVES (1). Equation of a plane progressive harmonic wave travelling along positive direction of X-axis is
y(x, t) a sin (kx t )
y(x, t) a sin(kx t )
And along negative direction of X-axis is
Where, y(x,t) Displacement as a function of position x and time t,
a Amplitude of the wave,
Angular frequency of the wave,
k Angular wave number,
(kx t ) Phase,
And Phase constant or initial phase angle (2). Angular wave number or propagation constant (k)
(3). Speed of a progressive wave
v
k
2
f k T
(4) Speed of a transverse wave on a stretched string
v
T
where, T Tension in the string, and Mass per unit length
(5). Speed of sound wave in a fluid
v
B
where, B Bulk modulus, and density of medium
(6). Speed of sound wave in metallic bar
v
Y
he e, Y = ou g s
odulus of elasti it of
etalli
a
. Speed of sou d i ai o gases Ne to s fo mula (connected)]
v
v
where, P Pressure, Density of air (or gas) and Atomicity of air (or gas)
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