Recording power and lumens for light bulbs.

[pebbles]

Homework Statement

Which is more efficient, or has the highest lm/W, a lower- or higher-power light bulb? To find out, look at bulbs and record the power and lumens.

Homework Equations

Lumen, lm, = P or luminous flux.

The Attempt at a Solution

Power of the light bulbs would be the number of watts, correct?
I am confused as to how to calculate the lumens of a light bulb. My teacher said that we can just look at bulb boxes at a store, so I know no measuring of surfaces is involved.


Thanks in advance.

 

[kamerling]

In europe, the number of Lumen will be present on the box.
I Have 2 boxes here that say:
230 V, 60 W, 710 Lumen
230 V, 100 W, 1340 Lumen
Kind of bulb: "Pearl"
so I don't think there is any calculation involved. I'd try to get some more datapoints

 

[Moetasim]

I would like to clarify a few points before providing a response. The term "efficient" can have different meanings in the context of light bulbs. Are you referring to energy efficiency, which would be measured in lumens per watt (lm/W)? Or are you referring to the overall effectiveness of the light bulb in terms of its brightness and ability to illuminate a space? Additionally, lumens are a measure of luminous flux, not power. Power is measured in watts, while luminous flux is measured in lumens.

To answer your question, a lower-power light bulb may have a higher lm/W ratio, meaning it is more energy efficient. However, a higher-power light bulb may have a higher lumen output, meaning it is brighter and more effective at illuminating a space. It ultimately depends on your definition of efficiency and what you are looking for in a light bulb.

To calculate the lumens of a light bulb, you can use the equation lm = P x luminous efficacy, where P is the power in watts and luminous efficacy is a measure of how well the light source converts electrical energy into visible light. The luminous efficacy can vary depending on the type of light bulb (incandescent, fluorescent, LED, etc.). Alternatively, you can also look at the lumen output listed on the light bulb packaging.

I hope this helps clarify the concepts and provides a starting point for your calculations. I would encourage you to continue exploring and learning about different types of light bulbs and their properties.