A student investigates how circuit arrangement influences the visual brightness of light-emitting filament bulbs.
• Circuit X: Two identical bulbs, each labelled “3.0 Ω when operating,” are connected in series to an ideal 6.0 V battery.
• Circuit Y: The same two bulbs are connected in parallel to an identical 6.0 V battery.
Assume each bulb quickly reaches its operating resistance and temperature in either circuit.
(a) Rank the four individual bulbs (the two in Circuit X and the two in Circuit Y) from brightest to dimmest. If any bulbs have identical brightness, state that clearly.
(b) Compare the current delivered by the battery in Circuit X with the current delivered by the battery in Circuit Y. State which battery provides the larger current and justify your answer qualitatively.
(c) Using energy considerations, explain why the observed brightness ranking in part (a) is consistent with your comparison of currents and potential differences in part (b). Your explanation should explicitly connect energy transferred per unit time to what is observed by the eye.