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A broadcasting station operates on two bands: AM at 1020 kHz and FM at 89.5 MHz. For efficient reception, which antenna arrangement is appropriate?

1. Use a longer antenna for the AM band and a shorter one for the FM band
2. Use a shorter antenna for the AM band and a longer one for the FM band
3. The same antenna length is suitable for both bands
4. The data provided is insufficient to decide

Correct answer: Use a longer antenna for the AM band and a shorter one for the FM band

Solution

Antenna size scales with wavelength. AM at 1020 kHz has a much longer wavelength than FM at 89.5 MHz, so AM needs a longer antenna and FM a shorter one.

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