Chapter 33, Problem 6RQ

To determine

The difference between apparent brightness and luminosity.

Answer to Problem 6RQ

Apparent brightness is the brightness of the star as it appears to the eyes, whereas luminosity is the total amount of energy emitted by the star into space

Explanation of Solution

Apparent Brightness	Luminosity
Apparent brightness is the brightness of a star as it appears to the eyes of the observer. It depends on the energy emitted by the star and also on the distance of the star from the Earth. For example, the apparent brightness of Betelgeuse is same as Procyon, whereas Betelgeuse emits 5000 times more light into space than Procyon.	Luminosity is the total amount of light energy that a star emits into space. It is always taken relative to the luminosity of Sun. For example, the luminosity of Betelgeuse is , which means it is 38000 times more luminous than Sun and emitting 38000 times the light into space as emitting by the Sun.

Conclusion:

Therefore, apparent brightness is the brightness of the star as it appears to the eyes, whereas luminosity is the total amount of energy emitted by the star into space.