P1 topic 1 & 2 Flashcards
wave
transfer of energy, information or data, but not matter
Amplitude
furthest point a particle gets from the equilibrium
oscillation
moving backwards/forwards or up/down around an equilibrium position
wavelength
distance from one point on the wave to the next consecutive similar point
frequency
how many whole waves go past a certain point per second
longitudinal waves
particles oscillate parallel to the direction of the wave e.g: primary seismic waves, water waves and sound waves
transverse waves
particles oscillate perpendicular to the direction of the wave e.g: secondary seismic waves, the electromagnetic spectrum
Retrograde motion
Mars
Kuiper belt
it consists of several frozen bodies orbiting beyond Neptune- it’s believed to be the source of all comets
who proposed the geocentric model of the solar system?
Ptolemy- it was used by the ancient Greeks
How did Ptolemy explain the occasional retrograde motion of Mars?
using epicycles
who proposed the heliocentric model of the universe?
Copernicus in the 14th century
What does the heliocentric model say about the stars?
they are in a fixed dome beyond Saturn
Why didn’t Copernicus’ model accurately predict the position of the planets
he used circular orbits
what did Kepler do?
in the 1600s, he realised that the planets had elliptical orbits
Who first observed the night sky using a telescope?
Galilei in the 17th century
What did Galilei see?
mountains on the moon and 4 moons orbiting Jupiter
Where does the asteroid belt lie?
between the orbits of Mars and Jupiter
How does the Hubble space telescope take pictures?
using visible light as well as ultraviolet and infrared
what other EM wave can be used to take pictures?
x rays
How do space observatories use infrared to produce images?
cooler objects emit more infrared than visible light- infrared astronomy was used to discover the Kuiper belt
where does a ray move relative to the normal when it slows down?
it bends towards the normal
what’s another name for a converging lens?
convex
what’s another name for a diverging lens?
concave
what are converging lenses used for)
to form images in telescopes, cameras, projectors, binoculars and our eyes
what happens to the focal length as the lens gets fatter?
it gets shorter
Oort Cloud
the outermost region of the solar system- this consists of billions of lumps of rock and ice
real image
an image formed on the other side of the lens to the object- a real image can be formed on a screen
virtual image
an image formed on the same side of the lens as the object- it can be seen by looking through lens but it can’t be projected into a screen
what type of images can a converging lens produce?
both magnified and diminished images, depending on position of object
what will happen when the distance between the object and the lens is greater than 2f?
image will be inverted, real and diminished
what will happen when the object distance is between f and 2f?
image will be inverted, real and magnified
what will happen when the object is closer to the lens than the focal length?
image is virtual, upright and magnified (this is a magnifying glass)
what made the image in early telescopes a bit blurred?
lenses have different focal points for different colours of light
how can a clearer image be formed?
by using a concave (parabolic) mirror in place of the objective lens
modern refracting telescopes
both objective and eyepiece lenses are converging- the objective lens produced an image of a distant object at its focal point, but the eyepiece magnifies the image
refracting telescopes vs reflecting telescopes
can be much larger and are easier to manoeuvre than refracting telescopes- this is because a mirror has a much smaller mass than a bulky lens
reflecting telescope
uses a large diverging/concave mirror, a plane mirror and a converging lens- the concave mirror fiend an image of a distant object, which is then reflected towards the eyepiece using the plane mirror
why are modern telescopes usually housed in observatories on high mountains?
little light pollution from cities, air is cooler so there is less interference from the atmosphere
waves
transfer energy and information from one place to another using vibrations, but they do not transfer matter in the direction that they are travelling
compressions
regions where particles are pushed together and create a region of higher pressure in a sound wave
rarefactions
regions where particles are pulled apart and create regions of low pressure in sound waves
where do rarefactions and compressions occur?
in longitudinal waves
what are seismic waves produced by?
earthquakes and explosions
how are seismic waves detected?
using a seismographs or seismometer
how is the vibration of the earth’a surface recorded?
by its motion relative to a heavy pendulum
Herschel
discovered infrared in 1800, whilst investigating the temp of visible spectrum- found hottest temp beyond red end of spectrum, where there was nothing visible- infrared have longer wavelengths than red light
Ritter
discovered uv in 1801, whilst experimenting with silver chloride used in photography- rate of reaction was faster beyond the violet end of the visible spectrum- uv have a shorter wavelength than violet light
what are the three types of UV waves?
UV-A, UV-B, UV-C
which UV waves have the shortest wavelength and therefore are the most harmful?
UV-C waves
electromagnetic waves
all are transverse and travel at the sand speed in a vacuum (300 000 000 m/s)
why are em waves transverse?
em waves consist of an oscillating electric field combined with an oscillating magnetic field- the 2 oscillating field are at right angled to each other and the direction of wave travel, so EM waves are transverse
