Download Physics Revision Questions

Physics Revision Questions – You must learn the answers to each of these questions
Question
Answer
1
What is the difference between the geocentric
and the heliocentric models of the universe?
The geocentric model has the earth at the centre of
the solar system and everything else orbiting around it.
Whereas the heliocentric has the sun at the centre and
the planets orbiting around it.
2
Why did Scientists change their opinion on the
model of the solar system from the geocentric
to the heliocentric?
Originally Scientists thought the earth was at the
centre of everything but by using telescopes to
observe and plot the movements of other planets this
was found to be incorrect.
3
Describe how Galileo’s observations of Jupiter
provided evidence of the heliocentric model of
the solar system.
Using a telescope Galileo plotted the movements of
Jupiter’s 4 moons around Jupiter thus proving not
everything orbits the earth.
4
How do Scientists observe the solar system and
the milky way today?
Relatively closer luminous objects in the solar system
give out visible light that can be observed using
telescopes on the earth or in space. Objects further
away in the milky way may give out only small
amounts of visible light so are better observed using
other types of telescopes that pick up radio waves or
microwaves.
5
What is a converging lens?
6
How do you measure the focal length of a
converging lens using a distant object?
A lens that makes light rays from a distant object bend
together and focuses them at a point a small distance
from the lens.
Clamp a lens and focus the image from a distant object
onto a fixed screen by moving the lens until a clear
image is formed. Measure the distance from the lens
to the screen, then repeat the experiment and average
the results.
7
What factors affect the magnification of a
converging lens?
How curved the surface of a lens is and how close
together lenses are placed.
8
What is the difference between a real and a
virtual image?
A real image is when the rays of light are bought
together by a lens and the image is observed on a
screen, whereas a virtual image is when the image is
observed on a surface like a mirror.
9
How does the eyepiece on a simple telescope
work?
The eyepiece lens is a small converging lens that is
used to magnify the image produced by the larger
converging lens at the other end of the telescope.
10
How does a reflecting telescope work?
A reflecting telescope uses a large curved mirror to
focus the rays from a distant object. Once focussed the
image is magnified using a converging eyepiece lens.
11
What happens to light as it passes from one
material to another?
Some of it will be reflected (bounced off) and some will
be refracted (bent).
12
What is refraction and what causes it?
Refraction is the bending (change of direction) of a
wave as it passes between different materials. It is
caused by the slowing down or speeding up of the
wave.
13
What do waves transfer?
Energy and information but not matter
14
Give examples of longitudinal waves (where the
direction of the vibration is the same as the
direction of energy travel).
Sound waves (including ultrasound and infrasound)
and seismic P (primary) waves.
15
Give examples of transverse waves (where the
direction of the vibration is perpendicular to
the direction of energy travel).
All of the electromagnetic waves including light etc and
seismic S (secondary) waves.
16
What are the standard units for speed?
Metres per second (m/s).
17
What are the standard units for distance?
Metres (m).
18
What are the standard units for time?
Seconds (s).
19
What is the frequency of a wave and what is it
measured in?
The number of waves in 1 second and the unit is Hertz
(Hz)
20
What is the wavelength and what is it
measured in?
The length of 1 complete wave cycle. It is measured in
meters (m).
21
What is the amplitude and what is it measured
in?
The distance from the centre of a wave to the top of
the wave. It is measured in meters (m).
22
As the wavelength of a wave increases, how is
its frequency changed? (Assuming that it is
travelling at a constant speed).
The frequency would decrease.
23
How did Herschel and Ritter discover waves
outside the limit of the visible spectrum?
Herschel noticed that if you split visible light up and
measured the temperatures of the different colours
the red light was hottest. He then moved the
thermometer just outside the red colour where he
could see no light and the thermometer recorded an
even higher temperature. He called this wave energy
Infrared.
Ritter also split visible light up but looked for wave
energy at the other end of the spectrum (the other
side of the violet light). He tried to detect the presence
of wave energy using silver chloride that he knew
reacted with violet light faster than red light. He found
that an unseen energy at this point in the spectrum
made the silver chloride react even quicker. He called
this energy Ultraviolet.
24
What are the colours of light in the visible
spectrum? (Start with the longest wavelength)
Red, Orange, Yellow, Green, Blue, Indigo, Violet.
25
What is the order of waves in the
electromagnetic spectrum? (Start with the
longest wavelength)
Radio waves, Microwaves, Infrared waves, Visible light,
Ultraviolet rays, X-rays, Gamma rays.
26
Are the electromagnetic waves transverse or
longitudinal
Transverse
27
Which travels faster in a vacuum light or radio
waves?
Neither, all electromagnetic waves travel at the same
speed in a vacuum.
28
Which end of the electromagnetic spectrum has
waves of the longest wavelength?
Radio waves
29
Which end of the electromagnetic spectrum has
waves of the highest frequency?
Gamma rays
30
What are the harmful effects of excessive
exposure to:
1. Microwaves
2. Infrared
3. Ultraviolet
4. X-rays and gamma rays?
31
As the frequency of a wave increases, what
happens to the potential danger?
32
Name some of the uses of:
1. Radio waves
2. Microwaves
3. Infrared
4. Visible light
5. Ultraviolet
6. X-rays
7. X-rays
33
Name 3 types of ionising radiation that transfer
energy?
Alpha particles, beta particles and gamma rays
34
Where does ionising radiation come from?
Radioactive sources continuously emit ionising
radiation.
35
What is the solar system and what is it part of?
It is made up of the sun and the 8 planets that orbit it
and it is part of the milky way galaxy.
36
What is a galaxy?
A collection of stars.
37
Put the following in order of size starting with
the smallest. Sun, universe, moon, planet,
galaxy, earth.
Moon, Planets (Earth), Sun, Galaxy, Universe.
1. Internal heating of body cells
2. Skin burns
3. Damage to surface cells and eyes, leading to
skin cancer and eye conditions
4. Mutation or damage to cells in the body
It increases too because of the increased energy.
1. Broadcasting, communications and satellite
transmissions.
2. Cooking, communications and satellite
transmissions
3. Cooking, thermal imaging, short range
communications, optical fibres, TV remote
controls and security systems.
4. Vision, photography and illumination.
5. Security marking, fluorescent lamps, detecting
forged bank notes, disinfecting water.
6. Observing the internal structure of objects,
airport security scanners and medical X-rays.
7. Sterilising food and medical equipment and
the detection of cancer and its treatment.
Most objects that astronomers observe give out
energy in all parts of the electromagnetic spectrum
and modern telescopes can detect almost all of it. Xray, ultra violet, radio waves are commonly detected
as well as light.
38
What other regions of the electromagnetic
spectrum are used by modern telescopes?
39
What methods are used to search for life
beyond earth?
Space probes orbit other planets like mars
photographing the surface so Scientists can decide
where water might have been. The scientists can
then land Landers to do soil experiments and look for
life in the most promising spots.
40
What is SETI?
The Search for Extraterrestrial Intelligence, it
analyses radio waves from space and look for signals
by intelligent beings. So far nothing has been
detected.
41
What is a spectrometer?
A device that can split up the different wavelengths
of light. (It splits light into its different colours).
42
Name a common object that could be used as a
spectrometer.
A CD or DVD or a prism (a triangular shaped piece of
glass).
43
What is the advantage of the Hubble space
telescope?
As it is situated above the atmosphere so that light
from distant objects enters it without being refracted
or reflected from out atmosphere which creates
clearer images.
44
Describe the life cycle of stars like our Sun
Stage 1: Nebula - a cloud of dust and gases (mainly
hydrogen) pulled together by gravity.
Stage 2: Star (main sequence) - As the nebula grows
the gravitational pull gets stronger and the pressure
and the heat builds resulting in the formation of a
star.
Stage 3: Red giant - When most of the hydrogen has
fused into helium the core collapses and the outer
layers expand.
Stage 4: White dwarf - The red dwarf throws off a
shell of gas and what remains will be pulled together
by gravity and collapses. No further reactions happen
inside a white dwarf.
45
How is the evolution of larger stars different?
Large stars become red super giants after the main
sequence. After the red super giant phase the star will
rapidly collapse and then explode (a supernova). If
what is left is 4 or more times the mass of our sun
gravity pulls the remains together to form a black hole.
If the remains are not that big gravity still pulls the
remains together to form a neutron star.
46
What is the Big Bang theory?
The whole universe started out as a tiny point of
concentrated energy about 13.5 billion years ago. Since
the big bang the universe has been expanding ever
since.
47
What is the Steady State theory?
The universe has always existed and has been
continuously expanding with new matter being created
as it expands.
48
Both theories believe the universe is expanding,
why is this?
When light from far away stars is split using a
spectrometer the light appears to have a longer
wavelength than we would expect (it is moved towards
the red end of the spectrum). This is called red shift
and can be explained if the source that is emitting the
light is moving away from us.
49
Why do we hear the Doppler effect when an
aircraft flies over us?
The aircraft is moving relative to us and so will have
higher frequency sound waves in front of it (because
the waves are compressed) and lower frequency waves
behind (because the waves are stretched). As the
aircraft passes us the pitch of the sound will decrease.
50
How do we know that galaxies further way
from us are moving faster than galaxies closer
to us?
51
Why do most Scientists believe the Big Bang
theory is correct?
52
What is Ultrasound?
53
Give uses of ultrasound.
54
What is Infrasound?
55
Give uses of infrasound.
56
57
What causes seismic waves?
Why is it difficult to predict earthquakes?
The faster a galaxy moves, the more red shift is seen.
Observations show us that there is more red shift from
more distant galaxies and so they must be moving
faster.
Microwave radiation can be observed all over the sky,
this is called Cosmic Microwave Background (CMB)
radiation. Its presence can be explained by the big
bang but not the steady state theory.
Sound with frequencies greater than 20 000 Hertz (Hz).
This is a range of frequencies greater than humans can
hear.
Sonar, communication between animals, foetal
scanning.
Sound with frequencies lower than 20 Hertz (Hz). This
is a range of frequencies less than humans can hear.
Communication between animals, detection of animal
movement in remote places, detection of volcanic
eruptions and meteors.
Earthquakes or explosions.
The earth’s tectonic plates are constantly moving and
there are never two occasions when the amount of
58
Name 2 types of seismic wave.
59
What causes these seismic waves to reflect and
refract?
60
How can the epicentre of an earth quake be
found?
61
Why do the earths tectonic plates move?
62
What can P-waves travel through?
63
What can S-waves travel through?
64
What causes an earthquake?
65
What is the difference between current and
voltage?
66
What is a renewable and non-renewable energy
source.
67
What are the advantages of non-renewable
sources of energy?
What are the disadvantages of renewable
sources of energy?
How can a current of electricity be Induced?
How can a larger current be induced?
68
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71
What is the difference between direct current
(DC) and alternating current (AC)?
72
What does a transformer do and how does it
work.
energy needed to move the surface is the same.
Longitudinal (P) waves and Transverse (S) waves.
(Where P = primary and s = secondary).
Both waves move through the centre of the earth
which is made of different materials. When these
waves reach a boundary they can be reflected or
refracted.
We know that P waves travel faster than S waves. Both
are produced at the same time so by measuring the
time difference between their arrival at the
seismometer, we can work out how far away the
epicentre is from the monitoring station. If there are at
least 3 monitoring stations the epicentre can then be
triangulated.
There are convection currents in the earth’s Mantle
(Hot liquid rock underneath the earth’s crust) that
force liquid rock up between plate boundaries forcing
the plates to move apart.
P-waves can travel through solid and liquid at speeds
of about 10km/s. So these waves can travel from one
side of earth through to the opposite point.
S-waves can travel through solids but NOT liquids at
speeds of about 6km/s. So these waves cannot travel
through the liquid outer core of the earth and cannot
be detected at the opposite point on the earth.
At plate boundaries, tectonic plates slide past one
another.
Current is the ‘rate of flow of charge’ and voltage is the
‘electrical pressure giving a measure of the energy
transferred’.
Non-renewable: Once it has been used it has been
effectively lost. (examples include coal, oil and gas
(fossil fuels) and uranium.)
Renewable: It can be used again and again. (examples
include: wind, wave, solar, geothermal, hydroelectric,
bio fuels etc.)
Possible to generate large amounts of electricity
reliably and relatively cheaply.
Not always reliable, often expensive, don’t generate a
lot of electricity in comparison to non-renewables.
By moving a magnet by a coil of wire.
By moving the magnet or coil faster, by using a bigger
coil or a stronger magnet (an electromagnet is
cheapest), putting an iron core inside the coil of wire.
DC is always in one direction. For example the current
from a battery or solar cell. AC changes polarity
because it is constantly changing direction. For
example in a generator.
A transformer changes the voltage of an AC supply.
73
Why is electrical energy transmitted at high
voltages?
74
Where would step up and step down
transformers be used in the national grid?
75
What unit is electrical energy from the mains
measured in?
What is power and what units is it measured
in?
What are the standard units for current?
76
77
78
79
80
81
82
83
What are the standard units for voltage?
When calculating the cost of electricity in £
what are the units for
a) Power
b) Time
c) Cost of 1kWh?
What are the standard units for energy
transferred?
What are the hazards of transmitting
electricity?
Low energy light bulbs cost more to buy than
filament lamps. Why are they considered
better?
84
85
How do you calculate the payback time for an
installation (in £)?
Can energy be created?
Name 9 different types of energy.
86
What is efficiency?
87
What unit do we usually use with efficiency?
To increase the voltage you need less coils of wire on
the left of the iron core and more on the right. This is a
step up transformer. To reduce the voltage the
opposite is true. This is a step down transformer.
An alternating current flows into the primary coil.
This makes a magnetic field in the core. The magnetic
field changes direction 100 times a second.
The changing magnetic field induces a current in the
secondary coil. The induced current is alternating too.
It improves efficiency by reducing heat loss in the
transmission lines by allowing a lower current to be
used.
Step up transformers are used in power stations
whereas step down transformers are used before
electricity enters factories and again before it enters
homes, offices and shops.
Kilowatt-hours
It is the rate of transferring energy. It is measured in
Watts (W).
amps (A).
Volts (V).
a) kilowatts (kW)
b) Hours (h)
c) Pounds (£)
Joules (J)
High voltages could cause electrocution.
The have a lower power rating and so they use less
energy per second. This makes them cheaper to run.
These bulbs last much longer and so as well as
reducing energy use they also reduce waste which is
better for the environment.
= Cost of installing (£)/Saving per year (£)
No, it can only be transferred. Energy is conserved.
Light, thermal (heat), sound, electrical, Kinetic
(movement), chemical, gravitational potential, elastic
potential, nuclear.
A measure of how much of the energy is transferred
into a useful energy type.
%
88
89
How does a system remain at a constant
temperature?
What type of surface best absorbs and emits
heat energy.
It needs to radiate the same average power (measured
in Watts (W)) as it absorbs.
A matt black surface.