Brightness of Light Bulbs in a Circuit

In summary, the conversation discusses how to determine which of five light bulbs will be the brightest in a circuit where four are connected in parallel and one is connected separately. The discussion involves calculating the total resistance and comparing the voltage drop across each bulb to determine its brightness. The value of the resistance is not necessary to know in order to compare brightness. However, the power dissipated by each bulb can be used to calculate the luminous flux or intensity, if more information is provided. It is also important to note that the brightness may not be directly proportional to voltage, as it depends on the power dissipated, which can vary depending on the type of bulb.
  • #1
ghostbuster25
102
0
Quick question, if i had a circuit of 5 light bulbs whereby 4 were running parellel in a sequence and one was running seperatly, would one be brighter than the others?
sorry if it is hard to visulise :)
 
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  • #2
I assume from your question that 4 bulb connected in parallel is in series with 5th bulb to a voltage source.
Now assuming all bulbs are identical, i.e., they have same resistances (say x) you can find the total resistance. And if you find voltage drop across these bulbs, you can find which bulb will be brighter.
 
  • #3
so shall i just substitute x into where the values of resistance would be. I am not given any values for anything
 
  • #4
Assume each bulb has resistance R and the whole circuit is driven by a source that produces V volts between its two terminals. Remember that the brightness is directly proportional to the power delivered to the bulb (assuming no or identical power loss).

Using these, you should be able to compare their brightnesses.
 
  • #5
No need to know the value of resistance, because you have to find which bulb is brighter and not how much right?
By simple common sense we know that the bulb with more voltage across it glows brighter. So you may check across which bulb more voltage drop will occur.
 
  • #6
n.karthick said:
No need to know the value of resistance, because you have to find which bulb is brighter and not how much right?

Even if you knew the value of the resistance, you will need to know much more to actually calculate a value for luminous flux or intensity. Comparison is the only sensible thing that I can see being done given only these pieces of information.

n.karthick said:
By simple common sense we know that the bulb with more voltage across it glows brighter. So you may check across which bulb more voltage drop will occur.

That is only true if the bulbs are identical. As I said the brightness is directly proportional to the power dissipated by the resistor inside the bulb. That's not a function of only the voltage across it. If you aren't convinced, you can easily try this by using two different light bulbs and a 9V battery.
 
  • #7
so am i right in believing it to be bulb p? the one on its own but in parallel with the others
 
  • #8
ghostbuster25 said:
so am i right in believing it to be bulb p? the one on its own but in parallel with the others

Which one are you referring to as bulb p?
 

FAQ: Brightness of Light Bulbs in a Circuit

What is the relationship between voltage and brightness in a light bulb circuit?

The brightness of a light bulb is directly proportional to the voltage applied to it in a circuit. This means that as the voltage increases, the brightness of the light bulb also increases. Similarly, decreasing the voltage will result in a decrease in brightness.

How does the wattage of a light bulb affect its brightness in a circuit?

The wattage of a light bulb is a measure of its power consumption. In a circuit, a higher wattage light bulb will draw more power and therefore produce a brighter light than a lower wattage bulb. However, it is important to note that the efficiency and design of the bulb also play a role in determining its brightness.

Can the type of light bulb affect its brightness in a circuit?

Yes, the type of light bulb can greatly affect its brightness in a circuit. Different types of bulbs, such as incandescent, fluorescent, and LED, have varying efficiencies and designs that can impact their brightness. For example, LED bulbs are known for their energy efficiency and can produce the same amount of brightness as a higher wattage incandescent bulb.

What is the role of resistance in determining the brightness of a light bulb in a circuit?

Resistance is a measure of how much a material resists the flow of electricity. In a circuit, the resistance of the light bulb affects the amount of current that can flow through it. A high resistance bulb will restrict the flow of current, resulting in a dimmer light. On the other hand, a low resistance bulb will allow more current to flow, producing a brighter light.

Can the brightness of a light bulb change in a circuit over time?

Yes, the brightness of a light bulb in a circuit can change over time. This can be due to factors such as the age and condition of the bulb, fluctuations in voltage, and the build-up of dust or debris on the bulb's surface. Regularly replacing old or damaged bulbs and keeping them clean can help maintain a consistent level of brightness in a circuit.

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