A simple circuit - 2 lamps in parallel connection dim

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Discussion Overview

The discussion revolves around the behavior of a simple circuit consisting of a battery and two light bulbs connected in parallel. Participants explore the reasons why both bulbs appear dimmer when connected together compared to when only one is used, delving into concepts of resistance, voltage, and current in electrical circuits.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the dimming of the bulbs is due to the internal resistance of the battery, which affects the voltage across the bulbs when a second bulb is added.
  • Another participant proposes that connecting the bulbs in series would keep them brighter, although this claim is contested by others who argue that series connections would actually result in dimmer bulbs.
  • A participant mentions a hypothetical scenario with specific resistance values and voltage, indicating that under certain conditions, the voltage and current could be the same regardless of the configuration.
  • It is noted that the resistance of the battery is typically much lower than that of the bulbs, suggesting that connecting bulbs in parallel may not significantly affect the current through each bulb.
  • Another point raised is that the resistance of the filament changes with temperature, which is influenced by the current, adding complexity to the analysis.

Areas of Agreement / Disagreement

Participants express differing views on the effects of connecting bulbs in series versus parallel, with no consensus reached on the optimal configuration for brightness. The discussion remains unresolved regarding the implications of internal battery resistance and the behavior of the circuit under different configurations.

Contextual Notes

Some assumptions about the circuit's configuration and the characteristics of the components are not fully explored, such as the specific internal resistance of the battery and the exact nature of the light bulbs' resistance under varying conditions.

fawk3s
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So I made this really simple circuit - a battery, some wires and a small light bulb. Now when I connected another light bulb with this light bulb, both of them where burning a tad dimmer than when there was only one lamp in the circuit.
Why is that? The voltage and the amperage should stay the same in both. Shouldnt they?

Thanks in advance,
fawk3s
 
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It's because of resistance in battery itself. You can model the behavior of real battery in a circuit by having a small resistance in series with an ideal battery. When you add a second bulb, current increases. That means higher voltage across resistor, and therefore, lower voltage across the two light bulbs.

You can alleviate that by adding a second battery in parallel with the original. The two light bulbs will then shine just as bright as a single light bulb with single battery.
 
Light bulbs are basically resistors. Perhaps this helps?
 
Does it not allso depend on how your simple circuit is configured.
Is the wireing in parallel or series.
Sorry seen the title me being dim.
Try connecting the lightbulbs in series pos battery, wire, lightbulb, wire, lightbulb, wire, battery neg.Should stay brighter.
 
Last edited:
K^2 said:
It's because of resistance in battery itself. You can model the behavior of real battery in a circuit by having a small resistance in series with an ideal battery. When you add a second bulb, current increases. That means higher voltage across resistor, and therefore, lower voltage across the two light bulbs.

You can alleviate that by adding a second battery in parallel with the original. The two light bulbs will then shine just as bright as a single light bulb with single battery.

Thanks mate, I think I get it.
 
Try connecting the lightbulbs in series pos battery, wire, lightbulb, wire, lightbulb, wire, battery neg.Should stay brighter.
No, if you connect them in series, they will be much dimmer, and likely won't light at all. You would effectively be cutting voltage across each one in half.
 
Mostly when connecting in series it will end up dimmer indeed. But when randomly calculating I found out that when playing around with 2 lightbulbs with resistance of 10 ohms, and a battery with 10 ohms, and with a voltage of 40 V, the voltage and amperage in both of the bulbs is the same, making no difference which way you connect them.
But these are, ofcourse, random numbers.
 
Keep in mind that realistically, the resistance in the battery is significantly lower than in a light bulb, so connecting multiple bulbs in parallel won't have as much of an effect on current through each as connecting them in series.

Also, the resistance in the filament depends on the temperature, and temperature depends on the current flowing through the filament. So that complicates things even more.
 

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