Two identical light bulbs are going to be connected to aconstant voltage source.

Question

Two identical light bulbs are going to be connected to aconstant voltage source. Will the bulbs provide more brightness ifthey are connected in series, or in parallel?

(a) The brightness is the same. (b) Series. (c) Parallel. I thought the answer was (b) more brightness if connectedin series, since V = IR, and assuming the voltage is the sameand that if it's connected in series there is less wire (i.e. lessresistance) and greater current (i.e. brighter). But I'm not sureif you can assume that just because it's in series there is lesswire than if it's in parallel. Can someone explain what the correctanswer is to me? Will rate lifesaver! Thanks! Two identical light bulbs are going to be connected to aconstant voltage source. Will the bulbs provide more brightness ifthey are connected in series, or in parallel?

(a) The brightness is the same. (b) Series. (c) Parallel. I thought the answer was (b) more brightness if connectedin series, since V = IR, and assuming the voltage is the sameand that if it's connected in series there is less wire (i.e. lessresistance) and greater current (i.e. brighter). But I'm not sureif you can assume that just because it's in series there is lesswire than if it's in parallel. Can someone explain what the correctanswer is to me? Will rate lifesaver! Thanks!

Explanation / Answer

think of brightness as being proportional to current. the more current, the brighter.
if the bulbs are in series and of the same resistance, thenthe total resistance in the circuit is 2R. using V=IR we findthat the current is going to be I=V/2R
now, lets look at the situation where the bulbs are inparallel. the total resistance for this circuit will now beR/2. this is because of how resistors add in parallel. the current is then I=2V/R.
so we can conclude that the current for the bulbs in parallelis double that of the bulbs in series. morecurrent = more power = more brightness

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