The speed of sound in air is around 330 m/s. If a bat emits a single high-pitched ‘click’ of sound in a cave that is 20m wide, calculate the time taken for the echo of the sound to return to the bat. Dolphins use seawater to transmit their high-frequency ‘clicks’. If a dolphin is 20 m away from an underwater object, deduce whether it will see the object sooner or later than the bat.
Suggest how an ultrasound scan can produce an image of an object within the human body.