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Homework Help: Electromagnetic Waves help

  1. Jun 8, 2004 #1
    First here is the question:

    Who will hear the voice of a singer first? A person in the balcony 50m away from the stage, or a person 3000km away at home whose ear is next to the radio? How much sooner? Assume the mic is a few cm from the singer and the temperature is 20 degrees celcius.

    Now I was able to calculate how long it would take for the person 50 m away to hear it, but I don't know how to find out how long it will take for the second person to hear it. Please help me. Which equation do it use?
  2. jcsd
  3. Jun 9, 2004 #2


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    The radio signal travels at the speed of light. I take it you are to assume that the singer's lips are close enough to the microphone and the hearer's ear is close enough to the radio that you can ignore those. The temperature is relevant to the speed of sound but not the speed of light.
  4. Jun 9, 2004 #3
    Shoot! I think I did it wrong. What would the speed of sound be at 20 degrees? I just thought the speed of sound would be the same as the speed of light. I guess I was wrong.
  5. Jun 9, 2004 #4
    wikidrox said, "I just thought the speed of sound would be the same as the speed of light."

    Not quite. Light travels about a million times faster than sound!
  6. Jun 9, 2004 #5
    Speed of Sound = 332 + 0.6T

    T = temperature in degrees celsius.
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