Due to skin effect in ac transmission..so Resistance of wire increase....we know>>>>> resistance in ac=1.5×resistance in dc

AC line requires more copper than a DC line

Introduction:
When it comes to transmitting power, both AC (alternating current) and DC (direct current) lines are used. However, the amount of copper required for transmission differs between the two. In this case, the correct answer is option 'B,' which states that an AC line requires more copper than a DC line. Let's delve into the reasons behind this.

Explanation:
There are several factors that contribute to the requirement of more copper in an AC line compared to a DC line for transmitting the same power. These factors include:

1. Skin Effect:
The skin effect is a phenomenon that occurs in AC transmission, where the current tends to concentrate near the surface of the conductor. This means that the effective cross-sectional area available for current flow is reduced, resulting in an increased resistance. As a result, more copper is required to compensate for this increased resistance and maintain efficient power transmission.

2. Voltage Regulation:
AC transmission lines are designed to transport power over long distances. To maintain voltage levels within acceptable limits, transformers are used. However, the presence of transformers introduces additional losses and requires more copper to compensate for these losses. In DC transmission, voltage regulation is more straightforward, and such losses are significantly reduced.

3. Reactive Power Requirements:
AC transmission involves the transfer of both real power (active power) and reactive power. Reactive power is required for voltage control and to support the operation of inductive and capacitive loads. Since reactive power is constantly oscillating in an AC line, it requires additional copper to compensate for the increased current and losses associated with it.

4. Transmission Line Impedance:
The impedance of an AC transmission line is typically higher compared to a DC line. Higher impedance leads to more power losses in the form of heat. To minimize these losses and maintain efficient power transmission, larger conductors (requiring more copper) are used in AC lines.

Conclusion:
In conclusion, an AC line requires more copper than a DC line for transmitting the same power. This is primarily due to the skin effect, voltage regulation losses, reactive power requirements, and higher transmission line impedance associated with AC transmission. By understanding these factors, engineers can design efficient power transmission systems while optimizing the amount of copper required.