ARRL Technician Practice Exam

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Prepare for the ARRL Technician Exam with detailed quizzes, flashcards, and explanations to boost your understanding and ensure success!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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How fast does a radio wave travel through free space?

At a speed greater than sound
At the speed of light
At half the speed of light
At the speed of sound

The correct answer is: At the speed of light

Radio waves travel through free space at the speed of light, which is approximately 299,792 kilometers per second (about 186,282 miles per second). This speed is a fundamental constant in physics, denoted as "c," and applies universally to all electromagnetic waves, including radio waves. In the electromagnetic spectrum, radio waves are just one type of wave, and they share the same speed as all other types of light waves in a vacuum. This property is crucial for radio communication, as it allows signals to be transmitted and received almost instantaneously over vast distances. The other options involve speeds associated with sound, but sound waves require a medium (such as air, water, or solid materials) to propagate and travel significantly slower than light. Sound travels at roughly 343 meters per second (about 1,125 feet per minute) in air at room temperature, which is vastly slower compared to the speed of light. Therefore, the assertion that radio waves travel at the speed of light is accurate and reflects a key concept in understanding radio transmission and propagation.