# Which bulb will glow brighter in a series and parallel circuit?

• Neha0555
In summary, Homework Equations states that: -Power is directly related to voltage -For series circuit, the 1000W bulb will glow more because power and resistance are directly related -For parallel circuit, resistance and power are inversely related and the one with higher power (1000W) will have less resistance and more current will flow through it
Neha0555
1. The problem, statement, all variables and given/known data
Say there are 3 bulbs of power 100W, 500W and 1000W connected in series. Which bulb will glow brighter and why? How would it be different for a parallel combination of these bulbs?

## Homework Equations

P=I^2R
P=V^2/RI think in series combination, the 1000W bulb will glow more because power and resistance are directly related in this case, and resistance is directly related to voltage. So, the one with higher power will glow more. For parallel combination, since voltage is constant across each bulb, I think we will take current into account. Here, resistance and power are inversely related, so the one with higher power (1000W) will have less resistance and more current will flow through it so it will glow more. Is it certain that P=I2R should be used for series circuit and P=V2/R should be used for parallel circuit?

Last edited:
The power ratings of bulbs come along with a voltage value. For example a bulb with rating 1000W,40V means that when 40V is supplied to the bulb, its power consumption will be 1000W.
Now ponder over this and you should arrive at the answer.

Neha0555 said:
P=RI
This should be P = IE, not ##P = R^I##.

Mark44 said:
This should be P = RI or IR, not ##R^I##.
How about ##P = I^2 R## ?

gneill said:
How about ##P = I^2 R## ?
My mistake. I was thinking P = IE but mistakenly wrote IR. I've fixed my earlier post.

ubergewehr273 said:
The power ratings of bulbs come along with a voltage value. For example a bulb with rating 1000W,40V means that when 40V is supplied to the bulb, its power consumption will be 1000W.
Now ponder over this and you should arrive at the answer.

Yes, and just to clarify for the purpose of this problem you must assume that all the bulbs are rated at the SAME voltage.

For problems like these they usually don’t explain that because they want you to realize that almost all household bulbs are (well, used to be) rated at the same voltage. 110V AC is the standard in the US. However, I think this problem is a bit of a cheat in that regard. I’m not familiar with many 500 and 1000W bulbs for the home, so if they aren’t household 110V bulbs how can you make the leap of faith that these are rated at the same voltage? Anyhow, that is just careless problem writing. Trust me, for this problem you have to assume the ratings are at the same voltage.

## 1. Which bulb glows brighter: LED or incandescent?

LED bulbs typically glow brighter than incandescent bulbs. This is because LED bulbs are more energy efficient and produce more light per watt of electricity used.

## 2. Does wattage affect the brightness of a bulb?

Yes, wattage does affect the brightness of a bulb. The higher the wattage, the brighter the bulb will be. However, this is not always true for LED bulbs as they are more energy efficient and can produce the same amount of light with lower wattage.

## 3. Are there other factors that can affect the brightness of a bulb?

Yes, there are other factors that can affect the brightness of a bulb, such as the type of bulb (incandescent, LED, fluorescent), the color temperature, and the quality of the bulb. Additionally, the environment in which the bulb is used can also impact its brightness.

## 4. Is brightness the same as luminosity?

No, brightness and luminosity are not the same. Brightness refers to the amount of light emitted by a bulb, while luminosity is a measure of the total amount of light energy emitted by an object, taking into account its surface area and distance from the observer.

## 5. How can I make my bulb appear brighter?

There are a few ways to make a bulb appear brighter. You can increase the wattage, choose a bulb with a higher color temperature, or place the bulb in a room with lighter walls and surfaces that can reflect more light. However, it is important to note that using a bulb with a higher wattage than recommended can be a fire hazard and may decrease the lifespan of the bulb.

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