Which of the following indicates a decrease in voltage in an electrical circuit?

A voltage drop occurs when there is a reduction in electrical potential along the path of a circuit. This can happen due to the resistance of the conductors, which causes some of the voltage to be lost as heat, especially when current is flowing. In a typical circuit, components such as resistors or long lengths of wire can introduce this effect, thereby reducing the voltage available at the load compared to what is supplied by the source.

The other terms refer to different phenomena: a voltage spike denotes a sudden increase in voltage, which can stress equipment and lead to failures; a voltage rise suggests an increase in voltage in part of the circuit; and voltage regulation refers to the ability of a power supply or electrical system to maintain a constant voltage despite variations in load current. Understanding these terms is crucial for diagnosing and designing effective electrical systems.