TPR Solution for Electric Circuit: Wrong or Right?

[ilovemcat]

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When I read this problem this was my thought process: If you decrease the amount of resistors within a parallel circuit, then each resistor remaining would receive a greater portion of current that enters the circuit. If each of the two remaining resistors, which in this case is the light bulb, both receive more current and the Power (light intensity) they would emit would be equal to P = I²‎ R . If current for each resistor in a parallel increases, then the intensity (power) of both light bulbs must increase. I don't understand why the answer wouldn't be C. If someone could help me understand, it would be greatly appreciated.

 

[SoftwareKevin]

When I read this problem this was my thought process: If you decrease the amount of resistors within a parallel circuit, then each resistor remaining would receive a greater portion of current that enters the circuit. If each of the two remaining resistors, which in this case is the light bulb, both receive more current and the Power (light intensity) they would emit would be equal to P = I²‎ R . If current for each resistor in a parallel increases, then the intensity (power) of both light bulbs must increase. I don't understand why the answer wouldn't be C. If someone could help me understand, it would be greatly appreciated.

You're right that the equivalent resistance of the parallel part of the circuit will change. This results in a change in the current supplied by the power source, NOT the current going through each light bulb. The current through each light bulb is *always* I = V / R. The voltage across a light bulb is constant no matter how many bulbs we have, and the resistance of each individual bulb stays the same... therefore current through each bulb remains the same.

You're also right that each bulb will receive a higher percentage of the total current... but the decrease in total current of the circuit balances this out

So the current supplied by the power source will go down, but the current through each light bulb remains the same.

 

[ilovemcat]

You're right that the equivalent resistance of the parallel part of the circuit will change. This results in a change in the current supplied by the power source, NOT the current going through each light bulb. The current through each light bulb is *always* I = V / R. The voltage across a light bulb is constant no matter how many bulbs we have, and the resistance of each individual bulb stays the same... therefore current through each bulb remains the same.

You're also right that each bulb will receive a higher percentage of the total current... but the decrease in total current of the circuit balances this out

So the current supplied by the power source will go down, but the current through each light bulb remains the same.

Ahhhhhh, I get it! Haha, thanks for the explanation!!