Deep Dive: E3A04
The correct answer is D: It travels at a right angle to the electric and magnetic fields. In what direction does an electromagnetic wave travel is that it travels at a right angle to the electric and magnetic fields. Electromagnetic waves propagate perpendicular to both the E and H fields. For amateur radio operators, this is fundamental electromagnetic theory. Understanding this helps when working with antennas and propagation.
Why Other Answers Are Wrong
Option A: Incorrect. Direction doesn't depend on phase angle of magnetic field - EM waves travel perpendicular to both fields. Phase angle isn't the factor. Option B: Incorrect. EM waves don't travel parallel to the fields - they travel perpendicular to both fields. Parallel is wrong. Option C: Incorrect. Direction doesn't depend on phase angle of electric field - EM waves travel perpendicular to both fields. Phase angle isn't the factor.
Exam Tip
EM wave direction = travels at right angle to electric and magnetic fields. Think 'E'lectromagnetic 'W'ave = 'E'lectric and 'M'agnetic fields, 'W'ave travels 'P'erpendicular. EM waves propagate perpendicular to both the E and H fields. Not phase angle, not parallel - just perpendicular.
Memory Aid
EM wave direction = travels at right angle to electric and magnetic fields. Think 'E'lectromagnetic 'W'ave = 'P'erpendicular. EM waves propagate perpendicular to both the E and H fields. Fundamental electromagnetic theory.
Real-World Example
An electromagnetic wave: The electric field (E) and magnetic field (H) are perpendicular to each other, and the wave travels at a right angle (perpendicular) to both fields. This is fundamental electromagnetic theory - the wave propagation direction is perpendicular to both field vectors. This is the direction - at a right angle to both fields.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E3A
Reference: 2024-2028 Question Pool · E3 - Radio Wave Propagation
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E3A topic.