Final answer:
The brightness of bulb B compared to bulb C when the switch is closed cannot be determined without knowing their power ratings.
Step-by-step explanation:
Without specific details about the resistances or the configuration of bulbs B and C, we cannot determine which bulb is brighter. Brightness depends on power consumption, which in turn depends on resistance, voltage, and current, factors which are not detailed for bulbs B and C.
When comparing the brightness of bulb B with that of bulb C in a circuit with a closed switch, several factors such as resistance, voltage, and current come into play. The brightness of a bulb is determined by its power consumption, which is given by the product of current and voltage (P=IV). Since the question does not provide specific details about the resistances or the configuration (series or parallel) of the bulbs, we cannot identify which bulb is brighter without additional information. However, we can draw on our understanding that in a parallel circuit, bulbs with lower resistance draw more current, resulting in greater brightness. Conversely, in a series circuit, the voltage drop across a bulb with higher resistance is greater, which can also lead to a comparatively brighter bulb, depending on the given resistance and voltage values.