Homework Statement
At time t=0, there is a missile at a height h directly above the perfectly round Earth moving tangential to the surface of Earth. What must be the maximum velocity of the missile at t=0 if it must land within radius r on Earth directly below its initial position by the time...
You might also want to check out the book by Mandel and Wolf called "Optical Coherence and Quantum Optics" if you're doing anything involving coherence and optics...
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...
While reading a paper on optics, I came across "the radiance of the projector is 20 mW/cm2, expanding out onto an f/18 cone."
What does the "expand out onto an f/18 cone" part mean? I thought that radiance is just in units of power/area/steradians. What does f-number have to do with anything?
Why can I occasionally hear myself through my cellphone when I'm talking to a friend? My own voice from the phone is just as loud as my friend's some of the time. How can I eliminate this phenomenon?
I think the error lies in that MATLAB treats * as matrix multiplication. In
> X = A*cos(w*T+pi)
the cos part is a 1x101 matrix (1 row, 101 columns) while the A part is a 1x13 matrix (1 row, 13 columns). Clearly, those can't multiply. You should probably just use a scalar for A. Then if you want...
Your boundary conditions will depend on your particular problem. Across a surface current (K) the boundary conditions are that the vector potential (A) above the current sheet is equal to vector potential below sheet. However, the derivative of A has a discontinuity:
\partial A_{above}/...
The reason Earth's magnetic field has a horizontal and vertical component is because it is oriented at angle with regard to the bar magnet in most places on Earth. Generally, you choose the reference frame to be that of the plane of the lab bar magnet. Of course you can also do it the other way...
While my friend was making a nice cup of British tea today, I noticed that when he put cold milk into the tea, it first sank but then almost immediately afterwards floated upwards. He thought it could be that the cold milk warmed up and hence floated to the top since warmer liquids are less...