Can someone explain how the laser pointer is generating the rectangular patterns shown in this youtube video?
I assume that there are just two diffraction gratings that are rotated relative to each other, but could someone explain mathematically how to predict what pattern is formed for...
I just read the following article about a book by Richard Muller.
http://www.npr.org/sections/13.7/2016/09/27/495608371/now-and-the-physics-of-time
What do you all think of it? Is this really a new idea?
"I think that only now can we finally understand the concept of now. In cosmology, we...
How can I find more information about where these transition frequencies would occur for air? I don't even know if they would be in the microwave/infrared/visible part of the spectrum.
Ah, that makes sense. So, say I want to actually go about building such a microphone. How could I calculate the amount of scattered light from an illuminated volume of air? Also, how does this depend on wavelength?
If such a microphone could be constructed it would have the benefit that there...
I've played around with taking piezoelectric transducers out of musical greeting cards. They are much better at picking up sounds through solids (like a stethoscope) than they are at picking up sounds transmitted through the air.
To hear the signal the piezoelectric disc is outputting you will...
I was wondering if it is possible to image the motion of individual air molecules? What I am picturing is using a laser to illuminate a volume of air, and using scattered light to measure the velocity of individual air molecules through the doppler shift of the scattered light. It seems that...
Thanks! I guess my question is more about the theoretical basis of the problem. If you have two tanks (T1 and T2) with volume V1 and V2 where V2>V1 and both with pressure Ph, and the goal is to maximize the pressure in a third tank with volume V3 and pressure P0 where P0<Ph, should you connect...
Ok! I was thinking that we should use the larger tank first. I was assuming the residual energy left in a tank is the product of its volume and pressure, so it would be more important to minimize the residual pressure in the larger tank.
My dad and I were going to fill up a tractor tire that was very flat. We had two air tanks, a small (~5 gallons) and a large air tank (~10 gallons) which were both filled to the same pressure (~100 PSI).
We wanted to pressurize the tractor tire as much as possible with the two tanks, and so my...
Interesting! Thanks for the input. Another question I have is if there is any way to calculate the approximate number of ions formed per second by a radiation source in air? I assume it only depends on the type of radiation, the intensity of radiation, and the pressure of the air.
From this I...
In a smoke detector there is 1 muCi of Am-241. I'm assuming that means it emits (3.7x10^10)*(1x10^-6)=3.7x10^4 alpha particles per second. Each alpha particle has a charge of 2e, so it seems to me that this stream of particles leaving the Am-241 pellet would carry a current of...
Hello everyone,
I have been playing around with Americium-241 from a smoke detector, and I was wondering where I could find a phosphorescent screen that would scintillate when hit with an alpha particle. Also, I was wondering what the different types of phosphor screens commonly used are and...
This is a problem I have never really understood. If a rocket engine is fired in a vacuum, does it exert the same force regardless of its velocity? If so, I don't know how to get around the following issue.
Say that the chemical energy stored in a particular rocket engine is 100 Joules (I am...