Final answer:
Bulbs connected in series receive a fraction of the source voltage, resulting in dimmer light. Bulbs connected in parallel receive full source voltage, operating at full rated power and glowing brighter.
Step-by-step explanation:
When three 100 W incandescent bulbs are connected in series, they will not glow with the same brightness as when another set of three bulbs with the same wattage are connected in parallel. In a series circuit, the same current passes through all the bulbs, and the voltage across each bulb is divided. However, given that the bulbs are designed for the full voltage of the source, each bulb in series gets only a fraction of the voltage, resulting in less power and dimmer light.
In contrast, in a parallel circuit, each bulb receives the full source voltage, and so operates at its rated 100 W power, assuming the power source can supply enough current. Consequently, the bulbs in parallel will glow brighter than the bulbs in series. The power output of each bulb is determined by the combination of voltage and current (P=VI), where P is power, V is voltage, and I is current. Since each bulb in parallel receives the full voltage, the resulting power, and thus brightness, will be higher compared to bulbs connected in series.
Understanding this concept is essential when considering how electric circuits are designed and how different configurations can significantly affect the performance of electrical devices such as light bulbs.