What is a common use for a step-up transformer?

A step-up transformer is specifically designed to increase the voltage from a lower level to a higher level. This increase in voltage is particularly useful in the context of electrical power transmission. By raising the voltage, the step-up transformer reduces the current needed to transmit electricity over long distances. This is crucial because higher voltage allows for energy to be transmitted more efficiently, minimizing power loss due to resistance in the wires.

For example, when electricity is generated at a power plant, the voltage is often stepped up to a very high level before it travels long distances through transmission lines. This high voltage is then stepped back down to a safer, usable level for homes and businesses at distribution points. The ability to boost voltage makes step-up transformers an essential component in the electrical power distribution infrastructure.

The other options relate to different electrical components and functionalities that do not involve the primary purpose of a step-up transformer. For instance, decreasing resistance, filtering noise, and rectifying voltage are specific processes handled by different devices in electrical engineering.