Angular Resolution Question (1 Viewer)

[frenzal_dude]

Hey, there are 2 formulas i know of for angular resolution, the one from excel is:
θ=1.22(λ/d)

and the one i learnt in class which is in the Jacaranda one is: (2.1 x 10^5λ)/d
But when i use both equations on a question, i get 2 different answers!

Example:

What is the theoretical resolution for the 300m radio telescope in Puerto Rico if it uses 4cm radio waves?

i get 28arcsecs with the Jacaranda one, but 33 arcsecs with the excel one.

Which one is right, and which formula should i use?

 

[currysauce]

do some questions, apply both formulas, see which gives the correct answer

 

[frenzal_dude]

but how do we know which 1 gives the right answer??

 

[la_mar]

It says in excel, θ is in radians.
While the R in jacaranda is in arcsecs

 

[rowan brand]

What the crap are you blokes talking about...... i dont have a clue? I am doing astro and what is all this aboyut... we didnt get taught this.... GAAHJHHHHHHHHH

 

[helper]

It is a formula that helps explain about aperature and resolution. It is not compulsory for the elective and will not be a calculation you have to do in the exam.

 

[DementedDonkey]

Hahaha... Rowan and I are in the same class, and both freaked out about this.. I love that not only do we have no idea about the formulae... but have never even heard of this in relation to astro - what a joke.

 

[frenzal_dude]

well its all in the text book, haha with physics and most other subjects, the teachers just go off the text book, the text book is really all you need, so if you got given that, then just read it, and if you don't understand it, then just ask a question here coz obviously your teacher has no clue.

 

[salsaDAVE]

nar frenzal, my teacher went off the sylabus, and theres nuttin in the sylabus about calculating angular resolution...

 

[great_guns]

there is stuff in the syllabus re angular calculations. how do you convert arcsecs into degrees? is it like x1/20 or sumfin?

 

[chinesefireball]

there is stuff in the syllabus re angular calculations. how do you convert arcsecs into degrees? is it like x1/20 or sumfin?

an arcminute is a 60th of a degree

an arcsecond is a 60th of a acrminute

 

[acullen]

nar frenzal, my teacher went off the sylabus, and theres nuttin in the sylabus about calculating angular resolution...

Haha, well it's good practice for the basic principles of diffraction for the photonics or modern physics section of the first year of a physics degree.