optic fibers are used for communication purposes instead of copper wires. the reason is that it reduces copper losses due to high frequency of the waves. How does optic fibers reduce the losses?do losses depend on frequency of the wave? since the equation for losses is given by I^2R the frequency has no role to play. is that so?
No. Look up 'skin effect'. It's the effect where high frequency ac currents are concentrated in the surface area of a metallic conductor. As the frequency of the ac goes up, the cross sectional area of the wire available to conduct that current is effectively reduced, increasing the apparent resistance of the conductor.
I^R refers to the electrical characteristics of a wire. Since fiber optics aren't electrical (they use light pulses through glass instead), the only line losses you get are from impurities or inclusions in the glass fiber.
The copper loss is not the driving force behind the use of fiber optic cable instead of copper. The prime reason is the quantum leap in data quantity handling capacity the fiber optic cable has over copper. High frequency signals carried on copper wire tend to travel on the surface of the wire as opposed to using the whole area of the wire. This coupled with the very rapid reversal of the current on the surface results in hysteresis losses in the wire, which is a real power loss.
