Solid angle Definition and 68 Threads

why solid angle is A/r^2 ...why is this r^2...has it any similarity with s=rtheta??please help me

where do we use solid angle or steradian for measuring,in what way is theuseful over normal angle?

I read in a paper the following passage: "We take the sun to subtend a linear angle of 32 arc-minutes. The solid angle is derived as \Omega=\pi sin^{2}16'=6.8x10^{-5} sr" I don't understand how the formula to go from linear angle to solid angle is just found by taking the area treating...

Hello. How does one derive the first formula on this page(the integral Omega = ...) http://en.wikipedia.org/wiki/Solid_angle" ? I guess the problem is to project some surface onto the unit sphere, so the formula makes sense with the dot product and all, but I just cannot derive it...

I am reading a book about integration on all possible momentum in 3D space, and it change the integration to a 1D integration and integration on solid angle, I don't know how does it happen \int d^3p \to \int p^2dp\int d\Omega where \Omega is the solid angle.

"flux per unit projected area per unit solid angle," L = \frac{\partial \Phi}{\partial \left(cos \Theta \right) \ \partial \Omega} What is this quantity? I mean, I know it's "flux per unit projected area per unit solid angle," how does the math work? I know it's not \frac{\partial...

What is a plane angle and a solid angle?(please provide diagram if possible) Also, what is the definition of 1 sr and 1 rad?

Homework Statement What are the units of solid angle in other systems ( In SI, it is steradian) Homework Equations The Attempt at a Solution

We describe mass as creating "curvature" in the universe. Taking a simplified lower dimensional analogy, the universe at a point in time could be seen on average as being like the surface of a ball, but at a more detailed level the surface could consist of shallow cones (made of locally flat...

Homework Statement How many inches from your face would you have to hold a dime in order for it to appear the exact same size as the Moon? Use a distance to the Moon of 384,400 km and a radius of the Moon of 1738 km. The diameter of a dime is 17.1 mm. (Hint: Find at what distance a dime has...

I am trying to work out the solid angle acceptance of a muon telescope. The telescope is comprised of two aligned square detector panels (of size x squared metres) set at a distance apart of L metres. The way I was initially working it out (by using the solid angle of a pyramid of base x...

well I can follow the math and derive the things I'm about to ask about and do problems asked of me but I'm kinda missing something, I guess Can someone just give me a fairly layman's explanation of: cross-section, differential cross-section, and a solid angle? Those are all things I thought...

Perhaps this should be moved to the math forum, but I've never quite been able to understand solid angles. For example, in terms of thermal radiation and the Planck distribution (black bodies), we can show that the energy flux denisty J_u (the rate of energy emission per unit area) is equal to...

This is the hardest brain teaser I could think of: ---------------- The solid angle of coffee is quite complicated. It involves some kind of resistance to change, and the density parameter for the brightness of stars is suprisingly inadequate. Unlike most people think, standard angular...

This isn't so much an astronomy question as one would think A perfectly black satellite is in orbit around the Earth at a height of 2000 km What solid angle does the Earth subtend when viewed from teh satellite? \cos \theta = \frac{6370km}{8370km} WEll if we look at hte diagram the angle...

So what i know that a solid angle is to sphere as the curve is to a circle... curve= rΘ, and (differential solid angle) dΩ=2ΠsinΘdΘ I need to prove it, and I'm a bit rusty and i donno where to start, i wonder if there's any usefull links or tips... Any more info about the use of a...

Hi, could someone explain to me the concept and calculation of Solid Angle? I don't think we've actually covered it in our Vector Calculus lectures and I have a question to do on it! Tried searching on the web, but not much information and I really don't understand it. Also, my question is...

In the following two questions, how would I find the solid angle at the origin? 1.Find the solid angle subtended at the orgin by the triangle with corners P=(1,0,0) Q=(0,1,0) and R=(0,0,1). 2.What is the solid angle subtented at the orgin by the plane x+y=4? For the second question...