homework help > physics > physics q&a board > topic: electromagnetic waves...

Q BgQuestion:

      
Novice
Karma Points: 25
Respect (73%):
posted by  Marshy on 11/5/2009 12:11:06 AM  |  status: Closed  |  Earned Karma: 25

Electromagnetic waves

Course Textbook Chapter Problem Needs by
Algebra Based Physics Physics (3rd) by Walker N/A N/A 11/5/2009 at 6:00:00 AM
Question Details:
A microwave transmitter emits electromagnetic waves of a single wavelength. The maximum electric field 1.22 km from the transmitter is 6.74 V/m. Assuming that the transmitter is a point source,
a. Calculate the maximum magnetic field at this distance. (2 points)
b. Calculate the total power emitted by the transmitter.
Bonus Point Alert! Earn +4 additional karma points for helping this gold member.

AAnswers:

Answer Question Ask for clarification
Oracle
Karma Points: 75,789
posted by watt (MNK) on 11/5/2009 12:20:21 AM  |  status: Live
Asker's Rating: Helpful   
Response Details:
a). Maximum electric field  E = 6.74 V / m
Maximum magnetic field  B = E / c
                                          = 6.74 / ( 3 * 10 ^ 8 )
                                          = 2.246 * 10 ^ -8 T
(b). Total power P = cεE ^ 2
where c = speed of EM wave = 3 * 10 ^ 8 m / s
        ε = permitivity of free space = 8.85 * 10 ^ -12 N m ^ 2 / C ^ 2
plug the values  P = 1206.1 * 10 ^ -4 W / m ^ 2
(SME)
Moderator
posted by Kevin_08 on 11/5/2009 12:24:57 AM  |  status: Live
Asker's Rating: Lifesaver   
Response Details:
   a)  The maximum magnetic field at this point is
                Bmax = Emax/c
                          = (6.74 V/m)/(3*108 m/s)
 b)  The total power emitted by the transmitter is
                     P = cεo Erms2 (4πr2)

  Here εo =8.85*10-12 C2/N.m2
              Erms  = Emas/√2
             r = 1.22*103m
  Substitute the values.
I hope this helps! Best of luck with the rest of your coursework.
Answer Question Ask for clarificarion
Ask New Question

Join Cramster's Community

Cramster.com brings together students, educators and subject enthusiasts in an online study community. With around-the-clock expert help and a community of over 100,000 knowledgeable members, you can find the help you need, whenever you need it. Join for free today » How Cramster is different from tutoring »

Need Help In

Useful Links