Some medical scanners produce radio waves at a specific frequency. Explain how radio waves are produced at a specific frequency.
How to approach this question
1. What fundamental process creates all electromagnetic waves? It involves charged particles.
2. What must these charged particles be doing?
3. How is the frequency of the wave related to the motion of these particles?
Full Answer
Electromagnetic waves, including radio waves, are generated by accelerating charged particles. In the case of radio waves, this is typically achieved in an electronic circuit with an antenna.
1. An alternating current (AC) is supplied to the antenna. An AC is a current where the charged particles (electrons) are constantly changing direction, causing them to oscillate or vibrate back and forth.
2. These oscillating electrons are accelerating charges, and they create changing electric and magnetic fields that radiate away from the antenna as an electromagnetic wave.
3. The frequency of the radio wave produced is determined by, and is exactly equal to, the frequency of the alternating current that causes the electrons to oscillate.
Common mistakes
✗ Just saying "from a transmitter" or "from an antenna" without explaining the underlying process.\n✗ Forgetting to mention oscillating/vibrating charges or electrons.\n✗ Not linking the wave frequency to the oscillation frequency.
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