wavelength in cable

It depends on the signal being transmitted through the wire-cable.

If it is an electric signal you have take electrons mass and size , current ,voltage , resistance ,capacitance , inductance into consideration , in the case of twisted pair cable.

If it is optical signal , as in optical fibre cable. you need to consider the refractive index , apart from the wavelength and velocity,single/multi-mode cable,refractive indices of the core,cladding,resonant frequency size of aperture .
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If it is a wave guide then the above formula is applicable with changes based on if it is:
Rectangular , circular , planar , etc. , resonant frequency , number of modes present in the wave guide.phase shift of the wave guide,type of mode propagating.

Please mention the type of the cable and its specifications , I hope to explain 😀

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