1Go to the nearest hospital or health institution and observe the ultrasonography machine kept in its laboratory. Ask the health workers there which conditions ultrasound is used to identify, and prepare a list.
2What is infrasonic sound? Write two natural events from which it comes out.
3What is the range of frequency a person can hear? Name the two kinds of sound that lie outside this range.
4Why does ultrasound carry a greater amount of energy? What is its wavelength like?
5Write four uses of ultrasound in the field of medicine.
6How does sonar measure the depth of the sea? Write it step by step.
7What is the difference between the frequency of a man's voice and a woman's voice?
8Why does the sharp voice of boys later become deep?
9A bat can fly in the dark without striking anything. Which kind of sound is this connected with?