Why are alternating currents used for power transmission?

Alternating currents are used for power transmission because they can be easily transformed to high voltages, reducing power loss during transmission.

Alternating current (AC) is the preferred method for power transmission for a number of reasons. The most significant of these is its ability to be transformed to high voltages. This is crucial for power transmission as it allows for the reduction of power loss during transmission. Power loss, also known as I^2R loss, is directly proportional to the square of the current. Therefore, by increasing the voltage (and consequently reducing the current), power loss can be minimised.

The transformation of voltages is achieved through the use of transformers. Transformers work on the principle of electromagnetic induction and can only function with alternating current. This is because a changing magnetic field, which is produced by an alternating current, is required to induce a voltage in the secondary coil of the transformer. Direct current (DC), on the other hand, cannot be transformed in this way as it does not produce a changing magnetic field.

Furthermore, alternating current is safer to use than direct current. This is because AC voltages can be easily stepped down to safer levels for use in homes and businesses. In contrast, high voltage direct current can be dangerous as it requires complex and expensive equipment to step down the voltage to safer levels.

Lastly, the generation of alternating current is more efficient than that of direct current. Most power stations generate electricity by rotating a coil in a magnetic field, which naturally produces an alternating current. Converting this to direct current would require additional steps and result in energy losses.

In conclusion, the use of alternating current for power transmission is primarily due to its ability to be easily transformed to high voltages, reducing power loss during transmission. Its compatibility with transformers, safety advantages, and efficient generation also contribute to its widespread use in power transmission.