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Homework Help: Electromagnetic Radiation

  1. Oct 31, 2005 #1
    I'm sorry if this isn't the correct place to put this...newbie alert.:biggrin: I'm absolutely horrible with Chemistry...I try really hard to do it, really I do, but a lot of the time, I only end up completely baffled and frustrated. Currently, I'm to be filling out a worksheet using a link provided in the lesson page (I'm cyber schooled) but the link is relatively short. I've read over it quite a few times but this stuff just doesn't make sense. I can't see what's being talked about and therefore I feel like I'm jumping into the middle of a subject that I missed the first half of...


    Why do we refer to radiation as "electromagnetic"?
    I'm supposed to read the info in this link http://www.chem.vt.edu/chem-ed/courses/spec/intro/em-rad.html" [Broken]. Actually, for this first question, I was advised to read just the first paragraph entitled Electromagnetic Radiation.

    Now, I've read that several times and it's making very little sense to me as, again, I can't see or even imagine what's being described. Would the first sentence be the answer to "why we refer to radiation as "electromagnetic"?

    I looked this up elsewhere and only ended up confusing myself...There are different types of radiation, right? Not just "electromagnetic". I'm looking at a list and it has Thermal radiation, Synchrotron, Gravitational, etc. It has Electromagnetic radiation listed as "Stream of photons of a variety of different energies. At low frequencies, such as radio, it is common to regard the radiation as continuous rather than as photons."

    Oh, I'm never going to get this...:cry: *Runs back into her English class*:tongue2:
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Oct 31, 2005 #2

    Physics Monkey

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    Hi AngelShare,

    Unfortunately, it looks to me like the link you were given isn't the best place to take a first look at electromagnetic radiation. Try this instead: http://www.colorado.edu/physics/2000/waves_particles/ [Broken] , I personally find the little interactive displays very fun.

    Don't give up! If the website isn't to your liking, then we can try something else. This stuff is understandable and fun if you can just get started, at least that's the opinion of a physics monkey.

    I can also address some of your questions right now. In short, electromagnetic radiation occurs when an object emits electromagnetic waves. Take a look at the above link to learn about these waves. Electromagnetic radiation is a very broad category, thermal radiation and synchrotron radiation are specific kinds of electromagnetic radiation. Gravitational radiation is something different that you don't need to worry about at this point. Here is a primer on radiation: http://www.uic.com.au/ral.htm
    Last edited by a moderator: May 2, 2017
  4. Oct 31, 2005 #3
    Ah, alright, that looks a bit more on my level.:rofl:

    What about the question though? It doesn't sound right... "Why do we refer to radiation as "electromagnetic"?":confused:

    I looked up "electromagnetic" and found this: "a fundamental physical force that is responsible for interactions between charged particles which occur because of their charge and for the emission and absorption of photons, that is about 100 times weaker than the strong force, and that extends over infinite distances but is dominant over atomic and molecular distances"

    Would that have anything to do with why radiation is called electromagnetic?
  5. Nov 1, 2005 #4
    Could someone please help me? Why in the world is radiation called electromagnetic? I really really need help with that...I'm afraid to move on without it because it may hinder me later on.:frown:
  6. Nov 1, 2005 #5
    That particular explaination is the definition of electromagnetic force and not what is actually an electromagnetic wave.

    Electromagnetic ray is basically a wave. I hope you know what a wave is . This wave is a bit different from other 2-D waves you studied at lower levels. This is an alternative wave such that 'Wave corresponding to electric field
    and the 'wave corresponding to electromagnetic field' flicker alternatively in prependicular planes, and the direction of propogation of this ray is given by cross product of E and B , the directions of E and the direction of B.

  7. Nov 1, 2005 #6
    See, that's a part of the problem. This class hasn't touched on this before, this is the first time. And, while I was still in my public school, I'm very sure we didn't touch any of this at all or I would have at least recognized it upon starting the lesson. My public school is behind the norm and my cyber school, I think, is a bit ahead of it as I find myself over-prepared for many of my tests so the transition between terribly easy and horridly hard is still taking its toll on me.

    Are there any others sites you'd suggest using to help me?
  8. Nov 2, 2005 #7


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    Just wondering, what is a cyber school like? Do you get to talk with your teachers? Do they have a home website where we could take a virtual tour?

    I was hoping to view the the link that Physics Monkey referenced, but both my browsers just close their windows when I try it, so I never get to that page. :uhh: (I use either Firefox or Mozilla). I can view the second one (the primer link) though, is that the one you said "is a bit more on my level? :rofl:" I see it is written in non-technical language.
    Last edited: Nov 2, 2005
  9. Nov 2, 2005 #8


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    First, you have to understand that electrically charged particles exist (electrons, protons, etc.). Electrical charge is a property of matter with certain observed properties. One of those properties is that a charged particle will exert a force on another charged particle. This is called the "electrical force." As a convenience in studying the electrical force, we talk about "electric field" which is the force produced by a unit of charge.

    Second, another property of an electrical charge is that when it moves about (i.e. we have an electrical current) the force it exerts on other charged particles behaves in a very different way. In addition to the electrical force, there is a new part called a magnetic force with a corresponding magnetic field. It's the same kind of force you observe with ordinary magnets like compass needles.

    Finally, when charged particles are agitated appropriately (i.e. accelerated!), the electrical and magnetic fields they produce merge in a very special way. They ripple through space emanating or radiating from the agitated charged particles and propagating out into the rest of the world. We call it a wave and because this wave is made up of electric and magnetic fields it is called an electromagnetic wave. It's sometimes also referred to as electromagnetic radiation because of the way it emanates radially out from the source.

    There are some other esoteric properties of EM waves relating to the relative orientation of the electric and magnetic fields and their direction of propagation but you have the basics here!
  10. Nov 2, 2005 #9
    Nope, my teachers don't have their own websites as most of them seem to teach at a regular school as well. I suppose I could post the link to my school's http://www.cpdlf.com" [Broken] is another I was considering but it costs...a lot.:tongue:

    If you have a pop-up blocker you may need to hold in Ctrl when clicking links.:smile:
    Last edited by a moderator: May 2, 2017
  11. Nov 2, 2005 #10
    Thank you so much, nice way to break it down.:smile:
  12. Nov 22, 2008 #11
    Hmm, I have this same exact question in Chemistry, except I'm taking it through FLVS(Florida Virtual School).
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