What determines the speed of electromagnetic waves through a medium?
The correct answer is D: The index of refraction. What determines the speed of electromagnetic waves through a medium is the index of refraction. The index of refraction determines how fast EM waves travel in a medium. For amateur radio operators, this is important for understanding propagation. Understanding this helps when working with different media.
Exam Tip
EM wave speed in medium = determined by index of refraction. Think 'E'M wave 'S'peed = 'I'ndex of 'R'efraction. The index of refraction determines how fast EM waves travel in a medium. Not resistance/reactance, not evanescence, not birefringence - just index of refraction.
Memory Aid
"EM wave speed in medium = determined by index of refraction. Think 'E'M wave 'S'peed = 'I'ndex. The index of refraction determines how fast EM waves travel in a medium. Important for understanding propagation."
Real-World Application
The speed of electromagnetic waves through a medium: It's determined by the index of refraction of that medium. For example, in air (index ≈ 1), waves travel at nearly the speed of light. In other media with higher indices, waves travel slower. This is what determines the speed - the index of refraction.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Resistance and reactance don't determine wave speed - index of refraction does. Resistance/reactance isn't the factor.
Option B: Incorrect. Evanescence doesn't determine wave speed - index of refraction does. Evanescence isn't the factor.
Option C: Incorrect. Birefringence doesn't determine wave speed - index of refraction does. Birefringence isn't the factor.
题目解析
The correct answer is D: The index of refraction. What determines the speed of electromagnetic waves through a medium is the index of refraction. The index of refraction determines how fast EM waves travel in a medium. For amateur radio operators, this is important for understanding propagation. Understanding this helps when working with different media.
考试技巧
EM wave speed in medium = determined by index of refraction. Think 'E'M wave 'S'peed = 'I'ndex of 'R'efraction. The index of refraction determines how fast EM waves travel in a medium. Not resistance/reactance, not evanescence, not birefringence - just index of refraction.
记忆口诀
EM wave speed in medium = determined by index of refraction. Think 'E'M wave 'S'peed = 'I'ndex. The index of refraction determines how fast EM waves travel in a medium. Important for understanding propagation.
实际应用示例
The speed of electromagnetic waves through a medium: It's determined by the index of refraction of that medium. For example, in air (index ≈ 1), waves travel at nearly the speed of light. In other media with higher indices, waves travel slower. This is what determines the speed - the index of refraction.
错误选项分析
Option A: Incorrect. Resistance and reactance don't determine wave speed - index of refraction does. Resistance/reactance isn't the factor. Option B: Incorrect. Evanescence doesn't determine wave speed - index of refraction does. Evanescence isn't the factor. Option C: Incorrect. Birefringence doesn't determine wave speed - index of refraction does. Birefringence isn't the factor.
知识点
Speed of electromagnetic waves, Medium, Index of refraction, Wave velocity
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.