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Waves
Waves

Group Velocity

vg=dωdkv_g = \frac{d\omega}{dk}

Velocity at which the envelope of a wave packet propagates; represents energy transfer speed.

Variables

v_g
Group velocity
Speed of wave packet/energy
m/s
ω
Angular frequency
Radians per second
rad/s
k
Wave number
Radians per meter
rad/m

Derivation

For dispersive media, v_g = dω/dk. For non-dispersive media, v_g = v_p.

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Common questions

What is the Group Velocity formula?

Group Velocity is written v_g = dω/dk. Velocity at which the envelope of a wave packet propagates; represents energy transfer speed. It belongs to Waves, under Wave Properties.

What are the units in v_g = dω/dk?

In SI units, v_g is group velocity, measured in m/s; ω is angular frequency, measured in rad/s; k is wave number, measured in rad/m.

How is the Group Velocity formula derived?

For dispersive media, v_g = dω/dk. For non-dispersive media, v_g = v_p. The result is v_g = dω/dk.