# Magnitude and Light brightness question

• LoveKnowledge
In summary, the conversation is discussing the intensity of light from multiple candle flames seen at different distances. The concept of intensity is defined as power/area and is proportional to distance. Therefore, the closer the candle flame is to the observer, the higher the intensity of light will be. In terms of the problem presented, the brightness would be ranked from brightest to dimmest as follows: 3 candles seen from a distance of 3 m, 2 candles seen from a distance of 2 m, and 1 candle seen from a distance of 1 m. This is in a 1-dimensional space. However, if we were to consider a 3-dimensional space, the ranking may change. Overall, the conversation is about understanding
LoveKnowledge
If I see 3 candles at 3 m across compared to 2 candles at 2 m across or 1 candle at 1 m across...does it make a difference in terms of brightness if more candles are seen at greater distances? Is the magnitude of light for all 3 situations the same?

Its about intensity, which is given by power/area is proportional to intensity. So technically, the nearer one will have its intensity higher. If we're considering a 3 dimensional space, which is in your question, then yes. If we're talking about 1 dimensional then no

quantumtron said:
Its about intensity, which is given by power/area is proportional to intensity. So technically, the nearer one will have its intensity higher. If we're considering a 3 dimensional space, which is in your question, then yes. If we're talking about 1 dimensional then no

Thx for your reply buddy. It is not a homework problem, it was in the review section and it confused me. The problem had stated: "Consider the light of multiple candle flames, each of the same brightness. Rank from brightest to dimmest the light that enters your eye for the following situations: a. 3 candles seen from a distance of 3 m. b. 2 candles seen from a distance of 2 m. c. I candle seen from a distance of 1 m."

So this is talking about 1-dimensional I think. I am just a little confused..this is a conceptual physics course and I want to make sure that I am understanding the concepts!

## 1. What is magnitude and how does it relate to light brightness?

Magnitude is a measure of how bright an object appears in the sky. In astronomy, it is used to describe the brightness of stars, galaxies, and other celestial objects. The lower the magnitude, the brighter the object appears. This means that a star with a magnitude of 1 is brighter than a star with a magnitude of 5.

## 2. How is magnitude measured?

Magnitude is measured using a logarithmic scale, with each whole number representing a difference in brightness of about 2.5 times. This means that a star with a magnitude of 1 is about 2.5 times brighter than a star with a magnitude of 2, and about 6.3 times brighter than a star with a magnitude of 3.

## 3. Is magnitude the same as luminosity?

No, magnitude and luminosity are not the same. Magnitude is a measure of how bright an object appears to us on Earth, while luminosity is a measure of the total amount of light a celestial object emits. Two objects may have the same magnitude, but one may be much more luminous than the other.

## 4. Can magnitude change for a given object?

Yes, the magnitude of an object can change over time. This can be due to various factors, such as the object's distance from Earth, changes in its brightness, or changes in the Earth's atmosphere affecting its apparent brightness. For example, a star may appear brighter when it is closer to Earth, or if it experiences a burst of energy.

## 5. How does the human eye perceive magnitude?

The human eye perceives magnitude logarithmically, meaning that a star with a magnitude of 1 will appear about 100 times brighter than a star with a magnitude of 6. This is because each whole number on the magnitude scale represents a difference of approximately 2.5 times in brightness, and the human eye can distinguish between a range of about 5 magnitudes. This means that the difference between a star with a magnitude of 1 and a star with a magnitude of 6 may not seem as significant to our eyes as the difference between a star with a magnitude of 1 and a star with a magnitude of 2.

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