Is the effective aperture of an antenna a constant?
When finding the effective aperture of an antenna we use: [tex]A_{eff}\;=\;D_0\frac{\lambda^2}{4\pi}\;\hbox{ where }\;\frac{\lambda^2}{4\pi}\;\hbox { is the effective aperture of a isotropic...
View ArticleThe period of an elastic band
Assume that a mass is attached to an elastic band and then allowed to oscillate. Would the formula for the period of oscillation be that as the same of the formula for the period of the oscillation for...
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Directional Derivative of Potential energy
I'm facing some problem in understanding few basic concepts of classical physics. I cannot understand what does "ij" indicate in "Vij" and how does F=-∇iVij. Why ∇i, why not only ∇. Please help...
View ArticleKepler's planetary motion and inverse square law
Hello, The inverse square law of Newton's gravitational force, is it somehow related to each other? I mean to say P^2 is directly prop.a^3. Is it from the third law that the derivation of inverse...
View Articleenergy and force
Hello all . I have two questions Energy can create force ? for apply a force we need energy ? Think about one electron , if you want to apply a force on it , you must have a particle in moving or a...
View ArticleCapacitor charged then disconnected
Hello, I am confused as to what happens when a capacitor is charged by a battery, disconnected, and then connected to a second uncharged capacitor. Is the situation different for whether the two...
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buoyant mass center
Hej Guys, I was wondering.. is it valid to calculate the buoyant mass center just as on the image? A hollow object hangs into the the water pool, I have a hard time to define what would be the buoyant...
View ArticleHow do you obtain electrons and know their average velocity??
Hello guys! I am currently trying to experiment with charge accelerators. I soon tripped inside a really big hole. I soon realized that I didn't know how to measure the amount of charge(in coulombs) a...
View ArticleCloaking Metamaterial Devices
Any decent links or papers about cloaking devices using negative refractive index metamaterials?
View ArticleElectrons in uniform magnetic field.
Hello. So I was wondering that when you shoot an electron through an uniform magnetic field, obviously Lorenz force starts to skew the path to that corkscrew shape that we all know. But then there is...
View ArticleClassical Nucleation theory two dimensions
Hi everyone, I'm having trouble understanding a problem on CNT in 2d. I'm given the equation [itex]\Delta G = \frac{4}{3} \pi R^3 \rho_s \Delta \mu + 4\pi R^2 \gamma[/itex] for nucleation in 3d. Here...
View ArticleA question about elastic collision of bodies.
English is not my native language. My question is about what happens when we throw a ball on the floor. I understand why the ball bounces off it. But I have a question, I wonder why almost all the...
View ArticleDichroic mirror spectral range?
Hi guys, I'm wondering about exactly if there is some sort of range that a dichroic mirror would reflect, like a green mirror would reflect between 532nm - 600nm or something. I'm pretty sure a green...
View ArticlePressure and energy correlation?
What's the correlation between energy and pressure? Is it E=P*V ? where E - energy, P - pressure, V - volume And for example lets say X represents Earth's atmosphere pressure and Y - pressure of the...
View Articlev*dv/dx for Acceleration
My mechanics syllabus suggests that we can model acceleration as ##v(dv/dx)## but what exactly does this mean? Can you give me (or link me to) some explanations and/or sample problems with worked...
View Articlethermodynamics: latent heat
I need some clarifications on the precise definitions and scope of latent heat. My textbook defines latent heat as the amount of energy absorbed or releases during a phase change process. So if I have...
View ArticleSize of a Magnetic field?
Hello! I was just wondering, how can one determine the size of an electromagnetic or regular magnetic field? For instance, if I had a regular bar magnet and I wanted to calculate to what distance the...
View ArticleWhat is the Height of EM Radiation
Hello, I have always wondered, what the relation of wavelength and frequency to the amplitude is. Is there an equation? Does it vary with different types of waves? Can it change?
View ArticleForce between a bar magnet and iron
I'm an inventor and I have an idea involving magnets. Unfortunately, I'm having a hard time trying to interpret magnetic equations. Please forgive me if I sound like a noob.. I'm new to magnetism. Lets...
View ArticleThe inertial frame trick.
Can anyone refer me to a discussion of applying the technique of changing reference frames to problem solving? Why it works, and what it means. I'm familiar with using it in some E&M problems, but...
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