There are two possible outcomes for this question: Yes and No. Yes, in the sense that the extension cord will undoubtedly use a small amount of electricity if it contains an indicator light. However, as a result, there will be a significant energy loss each year. However, if the extension chord lacks any indicator lighting, the answer is no—energy is not wasted. Similar circumstances apply to the wall socket, which uses no electricity while unplugged. Nevertheless, there will be a voltage drop due to the resistance of the conductors in the extension cord.