1. Tarnish Impact:
For audio frequencies (20 Hz - 20 kHz), the effect of tarnish on a 0.25 mm silver wire would be negligible. The tarnish layer, primarily silver sulfide, is still conductive, albeit less so than pure silver. The thin tarnish layer would not significantly affect the wire's overall conductivity or the signal transmission in the audio range.
2. Skin Effect:
At audio frequencies, the skin effect is minimal. Even if tarnish slightly alters the wire's surface conductivity, it wouldn't significantly impact signal propagation for audio frequencies.
3. Air vs. PTFE Dielectric:
The air dielectric, despite allowing for some tarnish formation, would still be preferable to PTFE for several reasons:
- Lower Dielectric Constant: Air has a dielectric constant very close to 1, while PTFE is around 2.1. This means less signal alteration and energy storage in the dielectric.
- Less Signal Smearing: Air introduces far less time smearing and phase distortion compared to solid dielectrics like PTFE.
- No Heat-Induced Tarnish: Unlike PTFE application, which can cause heat-induced tarnish during manufacturing, air dielectric allows the wire to remain in its original state.
4. Parallel Wire Configuration:
The presence of the larger 1 mm wire in parallel would further mitigate any minor effects of tarnish on the 0.25 mm wire, as the larger wire would carry most of the current due to its lower resistance.
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In conclusion, for audio frequency transmission, the slight tarnish on a 0.25 mm silver wire in an air dielectric would be far less detrimental than the combined effects of PTFE dielectric properties and potential heat-induced tarnish from PTFE application. The air dielectric configuration results in superior signal transmission characteristics for audio applications, even with some surface tarnish present.