# What is the meaning of luminosity per unit frequency?

• jmm5872
In summary, luminosity per unit frequency refers to the amount of energy emitted by a light source at a specific frequency or wavelength. It is a measure of the brightness of the light and is typically used in astronomy and physics to describe the intensity of radiation from stars and other celestial objects. It is important in understanding the properties and behavior of light and can be calculated using the Planck's law of radiation.
jmm5872
I am just trying to understand exactly what luminosity per unit frequency is. I know that luminosity (L = 4PI(r2)(flux)) is amount of energy per unit time, but not sure what it means when it is also per unit frequency.

The question has a cosmic source of 100 solar luminosity, all emitted with the frequency of 22 GHz, and the object is 0.001 pc in radius.

Do I calculate the luminosity (100*Solar Luminosity), actually I don't even know how to begin. I guess I am just confused at what exactly luminosity per unit frequency is and how to get it.

## What is luminosity per unit frequency?

Luminosity per unit frequency is a measure of the amount of energy emitted by an object at a particular frequency. It is typically denoted by the symbol Lν and is measured in units of watts per hertz.

## How is luminosity per unit frequency different from luminosity per unit wavelength?

Luminosity per unit frequency and luminosity per unit wavelength are two different ways of measuring the amount of energy emitted by an object. Luminosity per unit frequency takes into account the frequency of the light emitted, while luminosity per unit wavelength takes into account the wavelength of the light emitted. They are related by the formula Lλ = Lν * c/λ, where c is the speed of light.

## What is the significance of luminosity per unit frequency in astrophysics?

Luminosity per unit frequency is an important quantity in astrophysics as it allows us to compare the energy output of different objects at different frequencies. This can provide insights into the physical processes happening within these objects, such as the formation of stars or the evolution of galaxies.

## How is luminosity per unit frequency measured?

Luminosity per unit frequency is typically measured using telescopes and imaging instruments that can detect light at different frequencies. The total energy emitted by an object is measured and then divided by the frequency range to obtain the luminosity per unit frequency.

## Can luminosity per unit frequency vary for the same object?

Yes, the luminosity per unit frequency of an object can vary depending on the physical processes happening within the object. For example, a star may have a higher luminosity per unit frequency when it is undergoing nuclear fusion, compared to when it is in a quiescent state. Additionally, the distance of the object from Earth can also affect the measured luminosity per unit frequency.

• Introductory Physics Homework Help
Replies
1
Views
689
• Astronomy and Astrophysics
Replies
1
Views
2K
• Introductory Physics Homework Help
Replies
12
Views
1K
• Introductory Physics Homework Help
Replies
5
Views
1K
• Introductory Physics Homework Help
Replies
2
Views
974
• Introductory Physics Homework Help
Replies
10
Views
514
• Introductory Physics Homework Help
Replies
5
Views
3K
• Introductory Physics Homework Help
Replies
5
Views
1K
• Introductory Physics Homework Help
Replies
11
Views
2K
• Astronomy and Astrophysics
Replies
5
Views
4K