Ultrasound is used in liquid gold purification. It is also used for:

Correct answer: Prenatal Scanning. Ultrasound is widely used for prenatal scanning (checking an unborn baby).

Background: Ultrasound waves have frequencies above 20,000 Hz.

• Communication: Communication systems mainly use radio and electromagnetic waves.
• Radio Transmission: Radio transmission uses radio waves, not ultrasound.
• Fiber Optics: Fibre optics uses light, not ultrasound.

Did you know? Bats and dolphins use ultrasound to find objects.

Memory trick: Ultrasound scan = baby scan.