Waves for detection and exploration

echo sounding (ultrasound)

• ultrasound are very high frequency waves (so they have a short wavelength)

• this means they can be sent out as a narrow beam

• ultrasound can be used to measure distances as we know it’s speed in different materials

• echolocation is there and back so when calculating speed needs to be halved

• (use the eq S=D/T)

• used by bats

SONAR

• used by ships and submarines to detect objects underwater that we cannot see

• the wave reflects off of the object allowing us to calculate how far away it is

• sound navigation ranging (sonar)

ultrasound

• can be used for medical imaging

• waves emitted by transmitter

• when a wave crosses from one substance to another some of the wave is reflected

• → they are picked up by the receiver to build an image on screen

How is a computer able to build the picture of a baby using ultrasound scanning?

• waves only partially reflected → allows wave to continue to travel and reflect off multiple objects

• so different distances will reflect back at different times (eg scanning babies)

Name some advantages of using ultrasound instead of other methods of seeing inside the body eg x-ray when scanning a pregnant woman.

• no risks

• It does not use ionising radiation which could harm the developing baby

seismic waves

• produced by earthquakes in the Earth’s crust

• p-wave

• s-waves

P-waves

• longitudinal

• fast(er) moving

• travel through solids and liquids

• refracted so that there are zones where none are detected →indicates there’s a solid core

S-waves

• transverse

• slow(er) moving

• travel through solids only

• aren’t detected on the other side on the earth → suggests the outer core must contain liquid but the mantle has solid properties