Question

Given three light bulbs of the same resistance, how would you connect them to maximize the brightness of the bulbs? Draw a diagram using a power supply, wires and three light bulbs. Explain why this would yield the brightest configuration. Please type answer if possible! Will rate answer

Answer 1

The brightness of bulbs depends on power dissipation across it and power dissipation depends on "Resistance", voltage and current.

When bulbs are connected in series then overall resistance would be maximum (in given case 3R) and due to high resistance current would be minimum (I=V/3R in given case). Current remains same in series, so

Power dissipation across each bulb Pseries = I²R = (V/3R)²3R = V²/3R ------ (1)

When bulbs are connected in parallel then the overall resistance of circuit is minimum (in given case R/3) and overall current would be maximum (3V/R in this case) and as all bulbs are connected in parallel so current will get equally distributed. Current in each bulb is (V/R).

Power dissipation across each bulb Pparallel= i² R = (V/R)² R = V²/R ------ (2)

from equation (1) and (2)

Pparallel > Pseries; Hence bulbs will glow brighter in parallel combination .

(Detailed circuit- given in figure)

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