Physics quiz question: broadcasting from an electric dipole antenna

Physics 205B Quiz 1, spring semester 2014
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Multiple-Choice Question 22.1

A radio station uses a horizontal electric dipole antenna oriented east-west. It will broadcast most effectively to the __________ of its location.
(A) north and south.
(B) east and west.
(C) (Both of the above choices.)
(D) (No broadcasting is possible using this electric dipole antenna.)

Correct answer (highlight to unhide): (A)

An electric dipole antenna will broadcast most effectively in all directions perpendicular to its orientation, which for this horizontal east-west antenna would be to the north and to the south of its location (as well as directly overhead, or anywhere in the sky along a north-to-south line). There would be zero signal broadcast to the east and to the west of the antenna, as those locations would be looking at the antenna end-on, and there would be no detectable transverse oscillations.

Sections 30882, 30883
Exam code: quiz01ksB4
(A) : 34 students
(B) : 7 students
(C) : 0 students
(D) : 0 students

Success level: 83%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.17