Discussion
Copper behaves as a :
Answer: A
Copper behaves as a conductor or dielectric depending on the frequency.
Whether a material acts as a conductor or a dielectric depends on the ratio of conduction current to displacement current, \(\sigma/\omega\varepsilon\). For copper, \(\sigma \approx 5.8 \times 10^{7}\) S/m, so this ratio is enormous at all ordinary frequencies and copper is a good conductor. At extremely high frequencies, in the far ultraviolet and X-ray range, the ratio falls and copper behaves more like a dielectric, becoming partly transparent.
So copper is not a conductor 'always'. The classification depends on frequency, not on the applied field strength or the current density, since \(\sigma\) and \(\varepsilon\) do not change with these in ordinary conditions.
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