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Unformatted text preview: electric ﬁeld lines and equipotentials for the wire. Now assume that we place two thin wires of the same length, ‘ , end-to-end but not quite touching. This is called a “dipole antenna.” The ends of the wires closest to each other are called the “antenna feed” and they are the terminals where we would place a transmitter or receiver. (b) Assuming that the presence of the two wires do not inﬂuence each other (so that the ﬁeld distributions for each are the same you found for a single wire above), determine the voltage between the terminals of the dipole antenna in terms of the ﬁeld ~ E and the antenna length 2 ‘ . 3. A sphere of radius R carries a polarization, ~ P = k r ˆ r where k is a constant and r is the distance from the center of the sphere. (a) Find the bound charges, σ b and ρ b . (b) Find the ﬁeld inside and outside the sphere. 4. Cheng, P.3-22 . 5. Cheng, P.3-26 . 6. Cheng, P.3-28 ....
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- Fall '08
- Electromagnet, Electric charge, perfectly conducting spheres