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1). The "Opera" at 90.5 MHz has lower frequency,
so its wavelength is longer.
2). Whichever station is transmitting with higher power
has waves with higher energy.
Each photon of the transmission at 107.1 MHz carries more energy,
because the energy of a photon is proportional to its frequency.
But it's a mistake to think that the station at higher frequency has
waves with higher energy.