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|Velocity = what? X frequency
|Velocity = wavelength X frequency
|Units of frequency are?
|Hertz Hz or kiloHertz kHz
|If the source of a wave comes towards you, Doppler makes the frequency.......?
|Higher frequency when the source comes towards you.
|If the source of a wave goes away from you, Doppler makes the frequency.......?
|Lower frequency when the source moves away.
|If the source of a wave comes towards you, Doppler makes the wavelength ...........?
|Shorter wavelength if the source comes towards you.
|If the source of a wave moves away from you, Doppler makes the wavelength ...........?
|Longer wavelength if the source moves away from you.
|Which kind of wave is used to measure blood speeds?
|Which kind of wave is used to measure car speeds?
|If the light from a galaxy has a red shift, which way is it moving?
|Red shift means it is moving away from us.
|If the light from a star has a blue shift, which way is it moving?
|Blue shift means it is moving towards us.
|Two galaxies both have red shifts in the light we get from them. Galaxy A has twice the red shift that B has. What does this tell you about the speed?
|Twice the red shift means that galaxy A has twice the speed of B.
|What did Hubble discover about galaxy speeds and distances?
|That for most galaxies the speed a galaxy moves away from us is proportional to its distance.
|What does speed of recession mean?
|Speed something is moving away from observer.
|Hubble's Law is evidence that the universe is expanding. What did it start from?
|The Universe started from the Big Bang and has been expanding ever since.
|What kind of radiation was around just after the Big Bang?
|Very short wavelength gamma radiation.
|What has happened to the gamma radiation that was around at the start of the Universe?
|As the universe has expanded the original Doppler effect has expanded to microwaves.
|What does CMBR stand for?
|Cosmic Microwave Background radiation.
|Where does CMBR come from?
|Everywhere, in all directions.
|What is CMBR evidence for?
|CMBR is a second piece of evidence that supports the idea of the Big Bang.
|If CMBR is the second piece of evidence for Big Bang and universe expanding, what is the first?
|Hubble's discovery - most galaxies moving away, speed of recession is proportional to distance.
|What is ultrasound?
|Waves with a frequency that is above human hearing (over 20000 Hz)
|Blood, car and galaxy speeds. Which measurement does NOT rely on reflected waves?
|Galaxy speeds are measured from the light the stars in the galaxy give out.
|Ultrasound, microwaves, light. Which two have the same speed?
|Microwaves and light travel at the same speed.
|If ultrasound travels at 1500 m/s in blood, what is the wavelength of 300 000 Hz (300 kHz) waves?
|wavelength = speed/frequency = 1500/300 000 = 0.005 metres = 5 mm.
|why do we use ultrasound, not audible sound, to measure blood speeds?
|Wavelength of audible sound is too big for measurements inside body.