Letters on a radio switch

AMFM

["Think about the modes you can choose from when tuning a standard radio. What abbreviations represent them?"]

The clue "Letters on a radio switch" refers to the labels you’d see on an old-school radio dial for tuning into different frequency bands. "AM" and "FM" are the two main types of radio signals—AM for amplitude modulation and FM for frequency modulation—so the answer combines their initials as "AMFM." It’s a straightforward abbreviation, not a trick, just naming the letters you’d actually see on the switch. Think of the knobs or buttons on a vintage radio, and those four letters stand out.