Ultrasound close ultrasoundSound with a frequency greater than 20,000 Hz (20 kHz). is sound with a frequency greater than 20,000 Hz. Humans cannot hear ultrasound but many other animals can, such ...

AM (Amplitude Modulation) is a method of broadcasting radio and covers both Medium Wave (MW) and Long Wave (LW). Most AM radios have in-built aerials so the location of the radio is often the most ...