Why does the brightness of existing light bulbs not change when another light bulb is added in a...?

Question

parallel circuit? I know that the electrons have more than one path to flow and that the current is also divided according to the number of loads, but in a series circuit, isn't current and voltage also divided? Why is it that brightness is affected in one circuit and not the other? I was wondering if someone could explain this simply to me as I haven't learned about Ohm's Law and resistance yet.

Answer 1

Based on your phrasing we're dealing with the textbook "perfect wires" that have no resistance. In a perfect wire parallel circuit each bulb sees the power supply voltage directly at it's terminals. Adding or subtracting bulbs does not change the voltage seen by each bulb since every bulb has a direct path to both power supply terminals. If bulb 1 is alone and sees 12 volts it still sees 12 volts when you connect bulb 2 in parallel. Since the voltage at bulb 1 has not changed it's intensity does not change. If you transcribe a loop through each individual bulb circuit each loop has the same parameters, the source voltage is the same and the load (bulb) is the same so the power dissipated by the load (brightness in this case) must be the same. Because each bulb is the only load in it's loop the voltage is not divided among multiple loads regardless of how many loads. Current however is different. Each bulb will pass a given amount of current when connected directly to the source. The current seen at the power source is the sum of currents in each loop. If there are X bulbs, there exist X loops for current to flow. If each bulb draws Y current, the current provided by the source is X*Y. The current coming from the source divides through each individual load. If the current at the source is X*Y then the current in a single loop is 1/Xth of the total, or (1/X)*X*Y or simply, Y. (this is assuming all loads are equal devices) I'm trying to explain this without using Ohms law or Kirchoff's laws so it's too verbose.

In a series circuit there is only one loop for current to flow regardless how many loads are present. For this reason current does not divide in a series circuit, it has nowhere else to go. The voltage however does divide. The first terminal on the first bulb of the series circuit has the voltage potential of one terminal of the source, the last terminal on the last bulb of the chain has the potential of the other terminal of the source. The sum of voltages across each bulb must always equal the voltage of the source (V), no more, no less. If you have X bulbs and add one the voltage seen by each bulb goes from V/X to V/(X+1) which is some smaller value because the denominator is larger. If the voltage seen by each bulb in the new configuration drops the bulbs dim. If you take away a bulb the voltage seen by each remaining bulb goes from V/X to V/(X-1), a larger value, thus each bulb voltage rises, the remaining bulbs brighten.

Answer 2

In parallel circuits the potential difference in each branch is the same...Potential difference (pd) is the force exerted on the charge (electrons) by the cell...this remains the same as the charge moves through different paths...

so if identical two bulbs are in parallel same amount of charge will be flowing through it

and all the charge can give same amount of energy to the lamps they will have same brightness...

Answer 3

just cause in parallel connection voltage remains constant



cause in parallel connection only electrons divide but voltage is the potential energy of each electron remains means the energy causing electron to move remains same for all electrons causing constant voltage

for which current and resistance adjust them as v=ir hence if resistance increases then current decreases and put it in equation

h=i^2 rt

Answer 4

good. i'm no longer Unitarian yet i imagine theirs is the superb. I also like the Methodists. i'd upload in the Catholic church, alongside with candles they could have a ordinary bulb, notwithstanding that is the single genuine ordinary bulb and the bulbs of the Protestants does no longer really ordinary (pre Ecumenical Council Catholics)