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ฟิสิกส์โอลิมปิก วิทยาศาสตร์โอลิมปิก ข้อสอบแข่งขัน ข้อสอบชิงทุน => GRE - Physics => Topic started by: conantee on December 08, 2010, 01:40:19 AM



Title: GR9677.054
Post by: conantee on December 08, 2010, 01:40:19 AM
Question 54-55 concern a plane electromagnetic wave that is a superposition of two independent orthogonal plane waves and can be written as the real part of \vec{E} = \hat{x} E_1 \exp(i[kz -\omega t]) +\hat{y} E_2 \exp(i[kz-\omega t +\pi]), where k, \omega, E_1 and E_2 are real.

54. If E_2 = E_1, the tip of the electric field vector will describe a trajectory that, as viewed along the z-axis from positive z and looking toward the origin, is a
(A) line at 45^o to the +x-axis
(B) line at 135^o to the +x-axis
(C) clockwise circle
(D) counterclockwise circle
(E) random path