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I cant solve this MCQ, help please?

This is a question from June 13 . The answer is B. but how?

α-Centauri is one of the nearest stars to our Sun. The surface temperatures of these two
stars are about the same. α-Centauri has a 20% greater diameter than the Sun.
The ratio of the luminosity of α-Centauri to the luminosity of the Sun is about
A 1.2
B 1.4
C 1.7
D 2.1
Sorry you've not had any responses about this. :frown: Are you sure you’ve posted in the right place? Posting in the specific Study Help forum should help get responses. :redface:

I'm going to quote in Puddles the Monkey now so she can move your thread to the right place if it's needed. :h: :yy:

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Original post by Fatima SJ
This is a question from June 13 . The answer is B. but how?

α-Centauri is one of the nearest stars to our Sun. The surface temperatures of these two
stars are about the same. α-Centauri has a 20% greater diameter than the Sun.
The ratio of the luminosity of α-Centauri to the luminosity of the Sun is about
A 1.2
B 1.4
C 1.7
D 2.1


As they have the same temperature, the luminosity will depend on the area presented to the observer.
Area depends on radius or diameter squared.
20% greater means x 1.2
1.22 = 1.4 approx.
Original post by Stonebridge
As they have the same temperature, the luminosity will depend on the area presented to the observer.
Area depends on radius or diameter squared.
20% greater means x 1.2
1.22 = 1.4 approx.


Please refrain from posting full solutions.
Original post by Doctor_Einstein
Please refrain from posting full solutions.


This is not a full solution to a problem, it is an explanation of why an MCQ answer is what it is.
Educationally, totally different objectives.
Reply 5
Avatar for Fatima SJ
Fatima SJ
OP
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Original post by Stonebridge
As they have the same temperature, the luminosity will depend on the area presented to the observer.
Area depends on radius or diameter squared.
20% greater means x 1.2
1.22 = 1.4 approx.

Thanks alot :biggrin:

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