Transcript Physics 1 Revision Lesson 6 Sound and the Red shift

Physics 1 Revision
Lesson 6
Sound and the Red shift
Sound
Sound is a longitudinal wave
Sound waves cause vibrations in a medium, which are
detected as sound
direction of wave
pitch of a sound is determined by its
frequency and loudness by its amplitude.
The
Echoes are reflections of sounds
Red Shift
As the police car moves away from the standing girl,
the sound of the siren changes . This is because the
wavelength and frequency of the waves changes as
the police car drives away. This is called the
Doppler effect
If a star or galaxy is moving towards us, the light waves it
gives off are high in frequency
If a star or galaxy is moving away from us, the light waves it
gives off are low in frequency.
low
frequency light waves are red in colour
High frequency light waves are blue in colour and
The further away a galaxy is, the more the light is
shifted towards the red spectrum.
This means that the light from the galaxy must be
moving away from us, and therefore the whole galaxy
must be moving away from us. This is called
shift
G
G
Red shift!
G
red
The big bang theory
All matter starts from a single initial point
A massive explosion sends matter outwards
Causing universe to expand
Single initial
point
Massive explosion
Scientists have also detected
cosmic microwave background
radiation.
This is received from all parts of the Universe and is
thought to be the heat left over from the original
explosion.
Key words and
statements
Sound and the Red shift
Sound waves
As sound moves away or towards you the
frequency and wavelength changes. you hear this
as a change of tone
Doppler effect
A theory that states the universe began with a
single point explosion and is expanding
Echoes
Left over radiation from the big bang
Red shift
Are longitudinal waves which vibrate the particles
in the air. We hear this as sound
Blue shift
Are reflections of sound waves
Big bang theory
Galaxies moving towards us emit light (short
wavelength) shifted towards the blue spectrum
Cosmic microwave background radiation
Galaxies moving away from us emit light (long
wavelength) shifted towards the red spectrum
Sound and the Red shift
Sound waves
As sound moves away or towards you the
frequency and wavelength changes. you hear this
as a change of tone
Doppler effect
A theory that states the universe began with a
single point explosion and is expanding
Echoes
Left over radiation from the big bang
Red shift
Are longitudinal waves which vibrate the particles
in the air. We hear this as sound
Blue shift
Are reflections of sound waves
Big bang theory
Galaxies moving towards us emit light (short
wavelength) shifted towards the blue spectrum
Cosmic microwave background radiation
Galaxies moving away from us emit light (long
wavelength) shifted towards the red spectrum
Sound and the Red shift
The higher the amplitude…
The more high pitch the sound
The higher the frequency…
the light waves it gives off are low in frequency.
As the police car moves away from the standing
girl, the sound of the siren changes . This is
because …
Red shift and cosmic microwave background
radiation
If a star or galaxy is moving towards us…
The louder the sound
If a star or galaxy is moving away from us…
the wavelength and frequency of the waves
changes as the police car drives away
The further away a galaxy is…
the light waves it gives off are high in frequency
The big bang theory is supported by…
the more the light is shifted towards the red
spectrum
Sound and the Red shift
The higher the amplitude…
The more high pitch the sound
The higher the frequency…
the light waves it gives off are low in frequency.
As the police car moves away from the standing
girl, the sound of the siren changes . This is
because …
Red shift and cosmic microwave background
radiation
If a star or galaxy is moving towards us…
The louder the sound
If a star or galaxy is moving away from us…
the wavelength and frequency of the waves
changes as the police car drives away
The further away a galaxy is…
the light waves it gives off are high in frequency
The big bang theory is supported by…
the more the light is shifted towards the red
spectrum