Slides in this set
Ultrasound is sound frequencies higher than 20
We use ultrasound for pre-natal scanning of the
foetus because ultrasound waves can pass through
the body, however when they reach a boundary
between two different media (fluid in the womb
and the skin of foetus) some of the wave is
reflected back and detected.
Nobody knows for sure if ultrasound is safe, but X-
rays would be harmful to the foetus.…read more
Boats and submarines use sonar to detect things in
the water around them/
They emit waves of ultrasound which reflect off
things like other boats, the sea bed and marine
Animals like bats and dolphins use ultrasound to
sense their way around the environment in a similar
Many animals such as frogs, insects whales and even
rats use ultrasound to communicate which one
Sound that has a frequency below human hearing,
below 20 Hz, is called infrasound.
Infrasound waves have long wavelengths, this means
that they can travel long distances.
Elephants use infrasound to communicate with other
members of their herds over long distances.
Tigers also use infrasound in their roars and growls
so they can be heard by rivals or mates from far
When an earthquake happens seismic waves are
produced which travel; out through the earth.
P waves are longitudinal, they ravel through solids
and liquids and travel faster than S waves.
S waves are transverse, they only travel through
solids and they're slower than P waves.…read more