To operate a 6-volt lamp from a 120-volt AC source with minimal power waste, which device should be used?

Using a step-down transformer to operate a 6-volt lamp from a 120-volt AC source is a highly effective solution for minimizing power waste. The step-down transformer reduces the voltage from the higher AC input (120 volts) to the required lower voltage (6 volts) with high efficiency. This device does so by using electromagnetic induction, allowing it to provide the necessary voltage while also maintaining a proportionate current level.

When stepping down the voltage, the transformer ensures that the power delivered to the lamp is more aligned with its requirements, reducing excess energy dissipation that would otherwise occur if the lamp were connected directly to the higher voltage supply. Thus, the lamp operates optimally without the risk of damage from excessive voltage, while energy losses are kept to a minimum.

In contrast, the other options don't provide the same level of efficiency for this specific application. A current regulator primarily focuses on controlling the amount of current flowing in a circuit rather than reducing voltage. A voltage stabilizer is more about maintaining a consistent voltage level than stepping it down. A rectifier converts AC to DC and is not designed for voltage reduction in AC circuits. Hence, the step-down transformer is the appropriate choice for efficiently powering a 6-volt lamp from a