Corrections for paper 1 Flashcards
evidence for universe beginning at a single point. 5points
CMBR
microwave background radiation left over from beginning
the increase of recessional velocities with distance
microwaves because of cooling detected from all over the sky
how to determine critical angle
shine ray of light into block
through curved face
move raybox until angle of refraction is at 90 degrees
measure angle of incidence
beta decay
neutron decays to protons
beta emitted
investigating how the mass affects maximum vertical height reached by the trolley
measure mass of the trolley
measure verticle height using a ruler
repeat for a range of masses
evidence for universe expanding (8)
red shift
light from distant galaxies/stars
shifted to red side of em spectrum
observed wavelength of light is longer
all galaxies show this
Doppler effect
expanding at an increasing rate
conditions for nuclear fusion in a nebula
nebula collapses
under gravity
gpe converted into ke
or (1)
very high temperature/pressures reached
how are gamma rays produced (7)
gamma rays are often produced spontaneously/randomly
may result from radioactive decay
produced in the nucleus
produced by energy changes/rearrangement in the nucleus
gamma rays produced ti stabilise the nucleus
produced as a result of fission or fusion
gamma rays are produced in annihilation
how are radio waves produced (4)
radio waves are often produced intentionally by humans
produced by oscillating free electrons/alternating current
radio waves are produced in electrical circuits
aerials
Explain why the evidence available at the time supported the geocentric model.
- at the time, there was only
naked-eye evidence (1) - which indicated
Sun/Moon/planets appear to
move across the sky (1) - in the same direction, same
motion each day (1)
The Big Bang theory and the Steady State theory are two theories about the
origin of the universe.
The discovery of CMB led scientists to accept only one of the theories.
Explain why red shift supports both theories but CMB supports only one of them
both theories predict an
expanding universe and the
Big Bang theory also predicts
that the universe had a
beginning (1)
* the red shift theory indicates
that the universe is
expanding so supports both
theories (1)
* whereas CMB also indicates
that the universe had a
beginning, so supports Big
Bang theory (1)
(a) Describe how the student can determine the average speed of the trolley.
- measurement of time
between(or at) two
positions using
suitable timing
equipment (1) - measurement of
suitable distance
along the runway
with metre rule (1) - measurement of vertical
height to starting position
(1) - repeats AND averages
AND use of a correct
equation (1)
Devise an experiment that would allow him to investigate the effect of different
surfaces on the average speed of the trolley
Devise an experiment that would allow him to investigate the effect of different
surfaces on the average speed of the trolley
(i) Explain why a filament lamp appears brighter and less red as its temperature increases.
- intensity of radiation increases with temperature (1)
- the distribution of the emitted wavelengths of radiation is
affected by temperature (1) - at low temperatures the intensity of radiation emitted is
low and the (range of) emitted wavelengths (of
radiation) are high so the lamp appears dull red (1) - at higher temperatures the intensity of the radiation is
greater and the (range of) emitted wavelengths (of
radiation) are low so the lamp appear to be brighter and
less red (1)
Sulfates and black soot are particles formed by industrial processes.
Some of these particles are found in the atmosphere over the Arctic Ocean.
The sulfates stay in the atmosphere and reflect (scatter) sunlight.
The black soot falls onto the Arctic ice.
Discuss how a reduction in these industrial processes is likely to affect the
temperature of the atmosphere.
the soot could make the ice black
* black ice will absorb more IR radiation than white ice
* black ice might cause an increase in the temperature
of the Earth because absorption of IR radiation (can)
cause an increase in temperature
* reduction in soot might reduce warming because the
ice will not be as black/will be more white
* shiny sulfates (are good at) reflecting/scattering IR
radiation which means less heat absorbed
* sulfates scatter the IR and this reduces the amount of
IR radiation falling on the Earth
* sulfates might cause a decrease in the temperature of
the Earth
* reduction in sulfates might increase warming
Explain what happens to the wavelength of light when it passes from air into glass
- the wavelength
decreases because
wavelength is the ratio
of wave velocity to
frequency (1) - and the wave velocity
reduces at the boundary
but the frequency
remains the same (1)
velocity=frequency X wavelength
Figure 13 shows a beam of red light approaching one side of a rectangular glass block.
The beam of light will pass through the block and leave through the opposite side.
AB is a wavefront.
Discuss the path of the wavefront AB as it enters and leaves the glass block
point A reaches the glass block before point B
* A moves into the glass block and slows down
* as light travels more slowly in glass than in air
* B is still in air so is travelling faster than A
* this causes part of the wavefront to change direction/refract
* by the time B reaches the block it will have travelled further
than A
* therefore, the whole wavefront changes direction/refracts
towards the normal
* at the other face, A exits first so the process is reversed
* the wavefront changes direction again so it is parallel to its
original direction/refracts away from the normal
Uranium-235 is the isotope used in many nuclear reactors.
Explain how the fission of uranium-235 can lead to a chain reaction
causes 2 or 3 neutrons to
be released (1)
* (and) one or more of
these (released) neutrons
are absorbed by other (U)
nuclei (1)
* which cause further
fission of U nuclei (1)
* and release further
neutrons that can be
absorbed, causing a chain
reaction
Give a reason why a chain reaction can result from the emission of neutrons
by uranium nuclei but not by beryllium nuclei.
Idea that to get a chain reaction the particle that impacts
the nucleus must be the same as the one released (1)
Explain what happen inside a nuclear reactor if neutron speeds are not controlled.
- reaction will slow down
(1) - because there are fewer
fissions (1) - because fission more
likely with slow neutrons
Describe how the energy released in the chain reaction in a nuclear reactor is
used to drive a turbine in a nuclear power station
- the reactor is surrounded by a coolant (1)
- the thermal energy release from the chain reaction heats
the coolant (1) - the hot coolant is used to generate steam which is used
to drive the turbine (1)
