A good model for a radio antenna is a dipole. In the figure below P1 is on the p
ID: 2047042 • Letter: A
Question
A good model for a radio antenna is a dipole. In the figure below P1 is on the perpendicular bisector of the dipole, and P2 is along the axis of the dipole in the direction of the dipole vector pˆ. P1 and P2 are both a distance 100 m from the center of the dipole. The magnitude of each of the charges is 4.7 µC.?????
What is the magnitude of the electric field at P1? The direction of the dipole vector pˆ is from the negative charge to the positive charge. The value of the Coulomb constant is 8.99×109 N·m2/C2.
Explanation / Answer
the electric field of a dipole at any point at any point is given E = Kp(v1+3cas?^2)/r^3 --------------- (1) where K = 1/4pe and p = dipole moment(p= dq) (a) the electric field at P1, E1 = KP/r^3 (since ? = 90 degree) = 9*10^9*1.5*3.1*10^-6/ (100)^3 E1 = 41.85*10^-3 N/C the magnitude of the electric field at P1 is 41.85*10^-3 N/C . (b) the direction of the electric field ~E1 at P1: Ans: 1) In the direction opposite to that of the dipole vector; e.g., -ˆp (c) the magnitude of the electric field at P2, E2 = 2KP/r^3 (since ? = 0 degree) E2 = 83.7*10^-3 N/C (d) the direction of the electric field ~E2 at P2: Ans: 2) In the direction of the dipole vector; e.g., ˆp.