Em waves Definition and 219 Threads

Homework Statement Suppose that a police car on the highway is moving to the right at 28 m/s, while a speeder is coming up from almost directly behind at a speed of 34 m/s, both speeds being with respect to the ground. The police officer aims a radar gun at the speeder. Assume that the...

I'm attempting to calculate the above, but I'm stuck. What I have thus far: intensity is the time average of the poynting vector, where the poynting vector is the cross product of the E and B fields. Using the given expressions, I get: \frac{\sqrt{a^2 + b^2}}{\mu \omega} E_0^2 \exp(-2bz)...

Hi, if someone could help me figure this out I'd really appreciate it. Estimate the average power output of the Sun, given that about 1350 W/m^2 reaches the upper atmosphere of the Earth. I know the answer is 3.8 X 10^26 W but I don't know how to get there. I've tried different equations...

I have a little doubt. EM waves are coupled electric and magentic oscillations. But, to produce an electric field you need a charge and for a magnetic field, you need a moving charge ,but,electric field doesnot exist with a moving charge. So, what is the source of Em waves and moreover how...

just want to ask what are electromagnetic waves and how are they produced? also, do you where i can get a simple application of EM waves? just really need it... thanks!

I am doing a science fair project on refraction and I am preparing for the regionals and I found a small flaw in my report and I am wondering if any of you guys can help me out here. This is what I wrote: Why do electromagnetic waves warp when it goes through the process of refraction...

~5 qestions~ 1. EM wave can be reflected by metal surface only. Right? 2. SONAR can be reflected by any materials. Right? 3. Diffraction only occur when parallel wavefront(not circular wavefront) passes through the gap. Right? 4. After we use cloth to rub some substances, some are positive...

Electromagnetic waves interfere with each other. They cancel each other out. They can be complimentary or destructive, but they do interact with and change each other. If that's the case, with the plethora of electronic devices that surround us and the endless radio traffic we incessantly...

I'm reading an astronomy textbook, and I'm not sure about some things. The textbook says the EM waves are caused by accelerating charges. I don't understand how this is. I'm not sure, but my memory and intuition tells me that only charges moving in a sinuosidal (can never spell it) manner...

Text books talk about EM waves from moving charges, but don't mention EM waves radiating from a standing ie. not moving charge? I would think that for one standing charge to exert a force on a second standing charge, there must be a carrier particle/wave. Is this not an EM wave? Thanks! Jon

Could you please give me an explanation about this (it should be a basic question): why a slit with the width less than a EM wave wavelength does not allow the wave to go through? I know Hygen's interference rule but somehow I don't see that if the slit is less than a wavelength it completely...

why we should use the pulse function in function generator when we need to check the speed of electromagnetic wave in coaxial line ?? why we can't use the other like sawtooth function??

A Weird Idea Greetings. I have this idea, i know it is not really good (i already realized some of its weakness), but i thought i will put it here, since i believe that as it gets discussed (if it will) i might learn sth new. Ok, my idea is like a new way to make world-wide communication...

There are many properties of EM Waves that can be seen as some kind of ordered distribution of energy in space and time. I can think of a few: - Polarization: Direction of the electric field in space. - Coherence: Some kind of phase relationship My questions are: - How does a single...

I have an idea that I've tried to express on this forum before but without success. There's a lot of reasoning behind the idea so it won't do no good just blurting it out. I want to lead you and see if you reach the same conclusion... So here goes... First question... In classical physics...

[SOLVED] EM waves I have always been uncertain about what an EM wave consists of. I used to think it was a photon and somehow it carried properties of a wave. From reading some of the other posts on this forum, I'm realizing that I probably far off. So what is it? Does it have mass...

in all the articles i have read it is said that em waves are self sustaining, if this is corect then they are perpetual motion, i thought that was not allowed??

Hello, What is the max value of the eletric field at a distance 2.5m from 100W light bulb? I have the formula E_o = [squ]2S/e_oc. This is what i have so far... E_o = [squ]2(100W)/(8.85x10^-12C^2/Nm^2)(3x10^8m/s) = 274V/m. My calculations are not right can someone help me with solving...

Hiya! I have some general questions about EM waves since i am somewhat lost from reading and may have misuderstood what I read. 1) does all EM waves travel through a vacuum? if so are they the same speeds/proportional/inporportional to their frequency. 2) I now that EM waves are...