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# P2

Revision for AQA GCSE P2 module
by

## T Billimoria

on 30 November 2017

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#### Transcript of P2

P2
Forces
If two objects interact they exert an
equal
and
opposite
force on each other
resultant forces
If all of the forces acting on an object were replaced by a SINGLE force that had the same effect - this is the
resultant force
if resultant force = zero
1500N
1500N
stationary

If it was moving to start with, it will carry on moving at a
constant speed
in the
same direction
if resultant force = NOT zero
1500N
2500N
resultant forces always
change movement
- speed up, slow down or change direction
in this car, it will
accelerate
in the
direction of the resultant force
(right)....
ALWAYS
say which direction
the acceleration of an object depends
on its mass and the resultant force
bigger the mass, smaller
the acceleration
bigger the resultant force, bigger the acceleration
velocity and speed are both measure in metres per second (m/s).

Velocity is its speed in a given
direction
.
The acceleration of an object can be calculated using:
if the answer for acceleration is
negative
- it is
decelerating
Acceleration (or deceleration) is measured in
m/s
2
Distance-time graphs
horizontal line - stationary
straight line going up - constant speed

1. describe the motion

2. calculate the speed
from A-B and E-F

Velocity
-time graphs
horizontal line - constant velocity
straight line going up - accelerating
calculate area under - distance travelled
graph

1. describe the motion

2. calculate the acceleration and deceleration

3. calculate the distance travelled

ALWAYS DOUBLE CHECK
THE AXES OF THE GRAPH
at constant speed....
driving forces
=
resistive forces
(mostly air resistance)
when braking....
braking force
increases.
Work done
by the braking force
decreases the car's
kinetic energy
. As the kinetic energy goes down, the
temperature
of the brakes
increases
.
the
faster
the
speed
, the
bigger
the
braking force
needed to make the car stop in a
certain distance
.
faster vehicle increases both thinking and braking distance
thinking distance
is affected anything that affects the driver's
reaction time
: drugs, alcohol, tiredness

braking distance
is affected by wet/icy roads, smooth roads, worn brakes or tyres, how heavily loaded the car is
Thinking, braking and stopping are DISTANCES...not times
Weight
is the
force
exerted by gravity on an object
It is measured in
Newtons
, N

Mass
is the amount of matter that makes up an object. It is measured in
kilograms
, kg

Weight is calculated by:
On Earth,
g = 10 N/kg
always label an arrow
weight
not
gravity
do NOT write...."accelerates
at a constant speed"
A fluid could be a liquid (water) or a gas (air)
The
faster
an object moves through a fluid, the
bigger
the frictional forces on it.....
Falling objects accelerate
at the start due to weight

the faster they go, the
bigger the frictional forces
the resultant force
becomes zero
the object then moves at a constant speed (its terminal velocity)
like in the
skydiver....
Jumps out of plane..
weight
acts down, so
there is a
resultant force
so he
accelerates

The
faster
he goes, the
bigger
the force of air resistance.

So the
resultant force gets less
. His
rate of acceleration
gets
less
.

until...

...air resistance becomes
equal
to
weight.

There is
no
resultant force.

So, he travels at a
constant speed

(called terminal velocity).

then....

....the parachute opens.

Air resistance is now
bigger
than weight.

He
decelerates
rapidly.

But....the
slower
he goes, the
smaller
the force of air resistance.

The air resistance gets
less
until.....

....the two forces become
equal
again.

He travels at a new
constant speed
.

Forces can also change the
shape
of objects
When the force is applied, the object stretches, squashes or twists. If it is an
elastic object
it stores
elastic potential energy
when
work is done
to change its shape
an elastic object is an object that will return to its original shape when the force is removed

This graph can sometimes have the axes reversed
N/m
work done
means the
same as
energy transferred
work is done when a force moves an object through a distance
Work done against frictional forces cause energy to be transferred into heat

The crate and the floor get
hotter
power
is the
rate
that energy is transferred (how quickly)

It is measured in watts, W

This is also in P1 !!
Gravitational potential energy
Energy due to an objects position in a gravitational field.

If an object is lifted up
work is done
against gravitational force and the object
gains gravitational potential energy
.

kinetic energy
The kinetic energy of a moving object depends on
mass
and
speed
:

if mass is doubled, kinetic energy is....doubled
if speed is doubled, kinetic energy is...quadrupled (because it is squared)
Toyota Prius
has regenerative braking
If a moving car brakes, its
kinetic energy
is lost. It is wasted as
heat
in the brakes.

In regenerative braking, some of the kinetic energy lost when the brakes are applied is used to
charge a battery
.

This increases the
efficiency
of the car.
All moving things have momentum
p = m x v
momentum is like velocity - it has DIRECTION
It can be negative or positive (left or right)
INCREASING or DECREASING the momentum of an object needs a
resultant force
.

If there is no resultant force, the momentum will
stay the same
.
Conservation of momentum
learn this...
the momentum
before
a collision or explosion is
equal
to the momentum
after
a collision or explosion provided it is a closed system (
no external forces
act)
Maths problems on
conservation of momentum
Explanation problems on
conservation of momentum

the next video shows detailed
examples of solving problems
Before the explosion:
- rocket isn't moving (so
no momentum
)
- gases aren't moving (
so no momentum
)
This means the
TOTAL MOMENTUM BEFORE = ZERO

This means the
TOTAL MOMENTUM AFTER = ZERO

The only way the total momentum after the explosion can be zero, is if the
rocket goes in one direction
, and
the
gases go in the opposite direction
kg m/s kg m/s
To stop a car, the momentum has to
change
from a large value to
zero

A force is needed to do this

cars have special design features that crumple, crush or stretch

these
INCREASE the time
it takes for the
MOMENTUM to change to zero
so the
FORCE on the driver and passengers is LESS

this means they are less likey to suffer serious
injury
1
2
3
always say all three things!
Safety features of cars can be explained using
momentum
AND
energy changes
A person has
kinetic energy
in a moving car

this
kinetic energy
is lost in a collision

the kinetic energy
LOST
by the person is
GAINED
by the seat belt -
work is done
s..t..r..e..t..c..h..i..n..g the seat belt
When insulators are
rubbed
together they can become
electrically charged

Friction causes
negative electrons
to
move
from one material to the other.

The material that
GAINS
electrons becomes

negatively charged

The material that
LOSES
electrons becomes
positively charge

When two charged materials are brought together, they exert a
force
on each other

objects with the
opposite charge attract
(+ and -)

objects with the
same charge repel
(+ and + or - and -)
only t
he negative electrons move -
never
the positive protons
Charge and potential difference
Charges can move easily through conductors, like metals

Current is the
flow of charge

Charge will only flow between two points if there is a potential difference (or voltage)

Potential difference is the
work done
(or energy transferred)
per unit charge passing between two points

never say something has
no
charge - always say it has
equal
numbers of positive and negative charges
Do you know what all of these circuit symbols are for?
cells and batteries
A battery is two or more cells joined in series.

When cells are in series, you can add up the PD to find the total.....
BUT
this only works if they are joined correctly (positive to negative).
Where to put an ammeter and voltmeter

An
ammeter
measures the current
THROUGH
a component - so it must be put in
series

A
voltmeter
measures the potential difference
ACROSS
a component - so it must be put in
parallel
There are rules for
current
,
potential difference
and
resistance
in series and parallel circuits
in a series circuit
the total resistance is the
sum
of all the resistances
The
same current
flows through all components (remember I is the symbol for current)

I = 0.3A anywhere in the circuit
The
potential difference
of the power supply is
shared
between the components

If all the components (in this diagram the resistors) have the
same resistance
, they will all get the
same share

The
bigger the resistance
of a component, the
bigger the share
of the
PD
it gets

Could you say which of these resistors has the highest/lowest resistance?
in a parallel circuit
the
potential difference
across each parallel branch is the
same
the current
splits up
at branches

If the
resistance
of each branch is the
same
, they will all get the
same current
If the branches have
different resistances
, the
current
will be
different
in each branch.

The
bigger the resistance
of a component, the
smaller the current
flow.

The
total current
flowing can be found by
all the currents in the branches.

As the
free electrons

move through the metal (like a copper wire) they
collide
with the
ions
. This makes it difficult for the charge to flow. The
bigger the resistance
, the
smaller the current
.

This slowing down of current is called resistance.

Resistance is measured in
ohms, Ω
.

Resistance
Metals contains
free electrons
(charge) and
ions.
Current, potential difference and resistance are linked by the equation:
This is the experiment you would need to set up to find the resistance of a resistor...see where the ammeter and voltmeter are?
Guide to current and potential difference graphs
I, current
V, potential
difference
Current- potential difference
graph for a
resistor
Graph is....
A
straight line
going through the
origin
. This tells you current is
directly proportional
to potential difference (providing the
temperature is constant
).

The resistance stays the
same
.
A smaller value resistor will have a
STEEPER
graph
Current- potential difference graph for a
filament lamp
Graph is...
Curved. This tells you the resistance changes. Current is not proportional to PD.

As the
PD increases
, there are
more collisions
in the wire between the electrons and ions. This causes the
temperature to increases
and the
resistance increases
.
(flatter line)
means
BIGGER resistance
Current-potential difference
graph for a
diode
A diode only allows
current
to flow in
one direction
.
In the reverse direction it has very
high resistance
flat graph here = very high resistance
so....
how do you know which way
round to draw a diode in a circuit?
LEDs = Light emitting diodes
When an electric current flows through an LED in the forward direction it emits light. In the reverse it has high resistance so no current flows and the light is off.
Using

L
E
D
s

LEDs are expensive
use a smaller current than filament lamps - so use a smaller amount of energy
reliable
Thermistors and LDRs
These are made of materials that change their resistance in response to a change in environment (temperature or light intensity)
thermistor
LDR
The
resistance
of a
thermistor
decreases
as
the
temperature increases
The
resistance
of an LDR
decreases
as the
light intensity increases
thermistors are used as
temperature sensors....

LDRs are used as
light sensors...
Direct current (DC)
- from batteries
- flows in one direction

Alternating current (AC)
- from mains supply
- continuously changes direction
Finding the frequency and peak voltage

If the timebase (x-axis) is 0.1s
If the y axis setting is 3V
The
peak
(maximum) potential
difference is
6V

The
time period
is
0.3s

f = 1
= 1 =
3.3 Hz

T
0.3
3 x 0.1s
2 x 3V
T =

1
f
not
on the formula sheet
UK mains supply
230V 50Hz
Three-core cable
Three copper wires, each covered in plastic surrounded
by an outer plastic layer

Two-core cable
two copper wires, covered in plastic with an outer plastic layer. Only used in appliances that have an outside plastic case (no external metal)
The bigger the current...the thicker the cables need to be
...and the bigger the fuse needed
e
a
r
t
h w
i
r
e
neutral
wire
live wire
fuse
cable grip
wire are made of copper because...........................

cables are covered in plastic or rubber because.....

plug cases are made of plastic or rubber because..

pins are made of brass because..............................
...it is a conductor and it is flexible

...it is an insulator and can be flexible

...it is an insulator

...it is a conductor and a hard metal
A fuse will melts if the current is more than the current rating of the fuse
How a fuse and earth wire works....
The earth wire is connected to the
metal case
.
If there is a fault and the
live wire touches
the metal case, a
large current
flows down the
earth wire
. This causes the fuse to
melt
.
It is a large current because the
resistance
of the metal case is small.
Possible 4/5 mark question
double-insulated appliances
have this symbol on them
They have a plastic casing, not metal.
They do not have an earth wire because there
are no metal parts to become electrified.
They use two-core cable and often have
a plastic pin for an earth pin in the plug.
Residual current circuit breaker (RCCB)
Senses the difference in current between
the
live
and
neutral
wires.

In a normal circuit the current in both
wires is the same.

If the RCCB detects any difference in
current between the live and neutral it
breaks
the circuit.

Once the fault has been repaired, the button can be pressed to reset it.

RCCBs are
more sensitive
and
faster
acting than fuses.

Electrical energy transfer
All electrical appliances transfer energy

What is the energy transfer in each of these?

electrical energy to heat energy
electrical energy to light energy
electrical energy to heat energy
Calculating electrical energy transferred
How
much
electrical energy is transferred depends on:
1. the
potential difference
across the component
2. the
charge
flowing through the component
Power of electrical appliances

Power is measured in
watts
(W).

There are
two
formula you can use:
Filament lamps waste a lot of energy as heat - they are not very
efficient
Compact fluorescent
Lamps (CFLs)
waste less heat
energy
The atom
Small positively charged
nucleus
with
protons
(+) and
neutrons
.

Surrounded by electrons (-).
An
atom
has the
same number
of
protons
and
electrons - it has no overall charge
If an
atom
gains or loses an electron, it becomes an
ion

11 protons
11 electron
11 protons
12
electron
ATOM
ION
Mass number and atomic number
Isotopes have the
same number
of protons
but
different number of
neutrons
C C C
12 13 14
6 6 6
but...this wasn't always what we
thought that atoms were like
The
plum pudding model

by JJ Thompson, 1904
he thought atoms were like tiny
spheres of positive material
with
negative electrons embedded
in it.....like plums in a pudding
but then...
new evidence
came
along that caused this theory
to be
re-evaluated
Explaining Rutherford's experiment
Ruthford's gold foil experiment
results

to the
conclusions
What was the prediction of this experiment if Thompson's model was correct?
All
of the alpha particles would pass straight, or deflect
a little
, through the gold foil.

Rutherford's gold foil experiment
results
with the
conclusions

What were the actual
results
?
MOST
of the alpha particles went straight through the foil
SOME
of the alpha particles were scattered or deflected
A
FEW
of the alpha particles rebounded back
The nucleus must be
DENSE
because a small number of alpha particles were
repelled
, and rebounded back to where they came
The nucleus most be
POSITIVELY CHARGED
because some of the positively charged alpha particles had been repelled and
deflected
by a small angle
The nucleus must be
SMALL
compared to the whole atom because most of the alpha particles went
straight through
and were not deflected at all
Rutherford's model from the gold foil experiment is very similar to the one we still use today:
Many atoms have a nucleus
that doesn't change - it is
stable
.

Some nuclei are
unstable
. They will try to become stable by emitting nuclear radiation. There are three main types of nuclear radiation: an
alpha
particle (α) a
beta
particle (β) and a
gamma
ray (γ).

random
process - this means you cannot tell
when
a nucleus will decay

The rate at which the substance emits radiation (decays) doesn’t change, no matter what you do to the substance....like heat it up
alpha particle
This is the same as a
helium nucleus
. It has
2 protons and 2 neutrons
. There are no electrons (which is why it isn’t a helium atom)
A beta particle is a fast moving
electron
emitted from the
nucleus
of an atom
This is an
electromagnetic wave.

It is not a particle
beta particle
Alpha, beta and gamma can
remove electrons
from other atoms - this means that they can
ionise
the atoms.

Alpha particles have the
strongest ionising
power. This is because they are quite slow,
large
and
charged
.

Beta particles are
moderately ionising
.

weakly ionising
.

This explains their different properties
penetrating
through air and other materials.

SUMMARY
Deflection experiments
Alpha particles have a
charge
of +2.
Beta particles have a
charge
of -1.
no charge
.

Alpha and beta are deflected through magnetic or electric fields. Gamma
isn't
because it has no charge.

Beta and alpha are deflected in
opposite directions
because they have
opposite charge
.

Beta is
deflected more
(more curved), because it has a
smaller mass
than alpha.
Alpha decay
The nucleus loses an alpha particle -
2p and 2n
. The
mass number
goes down by
4
, the
atomic number
goes down by
2
.
Ra Rn + α
226
222
4
88
86
2
Beta decay
+
+
n p e
+
A
neutron
splits into a
proton
and an
electron
. The
proton
stays in the nucleus, the
electron
is fired out. The
mass numbe
r stays the
same
, the
atomic number
goes
up by one
.
C N + β
14
14
0
6
7
-1
No change
to the nucleus – it releases energy in the form of an
electromagnetic wave

Gamma is often given off at the
same time
as alpha or beta

m
m
m
Z
Low dose of radiation around us all of the time
higher
dose of background radiation because of:

where they live
(eg near granite rocks or high levels of radon)
their job
medical treatments
they might be having (radioactive treatments or diagnosis)
Half life
Carbon-dating - higher tier

Half life is the
time
it takes for the
number of radioactive nuclei in a sample to half

OR

Half life is the
time
it takes for the
count rate from a sample to fall to half
its initial value

It can be found from a graph....
Half-life always stays the
same
- 60 days for this isotope

Shorter the half-life, the
faster a nucleus decays
Different nuclei have
different half-lives - some
very
short
(fractions of a
second) some very
long

thousands of years).

Smoke detector

Killing bacteria

Killing cancer cells

Thickness control

The use of an isotope depends on its half-life and the type of radiation it emits (alpha, beta or gamma)

Could you pick the right isotope for a particular use, and explain
why you picked it?
alpha
source with a
long half-life - 460 years
alpha particles
ionise
the air - the air is
charged

if smoke gets in the way, it
reduces the amount of charged particles
in the air
the smoke detector picks this up and sounds the
alarm

gamma
source with a
long half life
gamma
kills tumour cells
must
rotate
the machine
so the tumour gets a large dose, but surrounding
healthy

tissue gets a
small
dose
gamma
source with a
long half-life
gamma
kills bacteria
to
sterilise
instruments or make
food last longer

Gamma
source (so it can
penetrate through the ground)
with a
short half life

There will be a high reading where the leak is
Only tracers
need
SHORT
half-lives

as they get
inside the
body

All other uses -
LONG
half-life
so it keeps working
effectively, and you
don't need to
replace it
Tracers - medical

Gamma
source - to
penetrate through
the skin
least ionising
short half life

injected or drunk for
diagnosis - eg to
monitor kidney function
long
half-life
source depends on the material...
thin paper - could use
alpha

thin aluminium (kitchen foil) - could use
beta

gamma

if
too much
radioactivity gets through from the emitter to the detector, the
computer
sends a signal to the
rollers
to
widen

if
too little
radioactivity gets through from the emitter to the detector then.....
if living cells are
ionised
, they can
mutate
and become
cancerous

There are ways to reduce exposure to nuclear radiation, especially if you work with them everyday.

Protective clothing -
remotely from a safe distance
Nuclear fission
Fission takes place in
nuclear power stations

Two fissionable substances:
uranium-235
and
plutonium-239

A
slow moving neutron
is fired at a large, unstable nucleus (uranium or plutonium)

It splits into
two smaller
nuclei
....

some
neutrons
...

and a
LOT of energy

In fission and fusion you
MUST
say nucleus or nuclei
NEVER
say atom or particle
This can cause a
chain reaction
as the new
neutrons go on to collide with other nuclei
Fusion takes place in
stars

Two
small nuclei fuse
together to make a larger
one. When this happens, a large amount of
energy
is released.

In stars
hydrogen
nuclei fuse to form
helium
.

Later on, fusion in stars produces
larger nuclei
like
carbon
and
oxygen
Cloud of dust and gas
attract due to
gravity

As they get closer, they get
faster and the
temperature
rises

It gets hotter and hotter until
it is a high enough temperature for..
...nuclear
fusion
to happen

H fuses together to form He

producing lots of heat/light energy

Star is
stable

Inward forces = outward forces

Inward forces = gravity
Outward forces = high temperature and pressure

Star
runs out
of hydrogen fuel

Starts to fuse
helium
and other elements to form oxygen, carbon and heavier elements up to iron

It
expands
because forces are no longer
balanced

It
cools
down (which is why it turns red)

Red Giant or Red Supergiant stage
fuel runs out...star contracts
due to gravity to form a dense....
it then fades to become a dense, black dwarf
That is the life cycle of a small star (like our Sun)

If the cloud of dust and gas is big enough...
...nuclear
fusion
to happen

H
fuses
together to form He

producing lots of
heat/light energy
- burns
brighter
, hotter and shorter than a small star

Star is
stable

Inward forces = outward forces

Inward forces = gravity
Outward forces = high temperature and pressure
ure and pressure

Star
runs out
of hydrogen fuel

Starts to fuse
helium
and other elements to form oxygen, carbon and heavier elements up to iron

It
expands
(much bigger than for a small star) because forces are no longer
balanced

It
cools
down (which is why it turns red)

Red Giant or Red Supergiant stage
As the fuel runs out it starts to collapse

The outer layers
EXPLODE
(called a supernova)

There is a large amount of
energy
released in a supernova

Elements heavier than iron
, like gold and uranium can only be formed in a supernova

The explosion scatters these new elements into the Universe

Heavier elements are found in our Sun, on Earth and on the planets of our solar system.....which shows we have been recycled from a supernova!

What is left collapses due to gravity to form a
dense
neutron star

Or, if there is enough mass, it will collapse to form a
dense
black hole

The gravity from a black hole is so strong,not even light can escape
Right.....now for some practice questions
Describe the motion of a car if the forces acting on it are balanced
Describe the motion of a car if the
forces acting on it are unbalanced
What is the formula that links resultant force,
mass and acceleration?
What does resultant force mean?
What are the units for velocity?
How are speed and velocity different?
If a resultant force is acting on something,
what can it cause to happen?
In an elastic object, what is the relationship between force and extension?
what does limit of proportionality mean?
What does elastic mean?
What type of energy is stored in
a stretched spring?
What does a horizontal line mean:
(a) in a distance-time graph
(b) in a velocity-time graph
What does a straight diagonal line
pointing upwards mean:
(a) in a distance-time graph
(b) in a velocity-time graph
What does the gradient of a
distance-time graph tell you?
What does the gradient of a
velocity-time graph tell you?
What does the area under a
velocity-time graph tell you?
What would a steeper line tell you
in:
(a) a distance-time graph
(b) a velocity-time graph
What would a bigger area under
a velocity-time graph tell you?
Work is done when a car brakes. Why?
What is braking distance?
What is thinking distance?
What factors affect thinking distance?
What factors affect braking distance?
How does speed affect the braking
force needed to stop a car?
name two fluids
What happens to the frictional forces
as an object moves faster through a fluid?
What is the difference
between mass and weight?
Name the forces acting on a cyclist. Describe
fully how these forces change as he gets faster
until he reaches his maximum speed
Name the forces acting on a ball falling through
a measuring cylinder of liquid. Describe fully how these forces change as it falls.
Explain how the forces acting on a sky-diver change after he jumps out of the plane

Sketch the velocity-time graph for a sky-diver
What is work done? What is it
another name for? What is
it measured in?
What two formulae could be used
to find the acceleration of a car?
What is power?
What formula could you use to calculate power?
What is power measured in?
What affects how much gravitational
potential energy something has?
What affects how much kinetic energy something has ?
Why does speed have more of an effect
on kinetic energy than mass?
What is regenerative braking?
Why is it a good thing?
How are momentum and velocity similar?
How would you calculate momentum?
What are the units of momentum?
What is the law of conservation of momentum?
Why do airbags reduce injury?
If a person is wearing a seat belt in an accident,
where does their kinetic energy go?
If a polythene rod becomes negatively charged
when it is rubbed with a cloth...what happened?
What happens if two negatively
charged balloons are brought
close together?
What is the definition of current?
What is the definition
of potential difference?
What formula would you use to calculate
the charge ?
Do you know what all of these circuit symbols are for?
What would the total PD be
if you had four 1.5V cells in series?
What would the total PD be if you
turned one of them around?
What are the rules for current in:
(a) a series circuit
(b) a parallel circuit
If there was 2A flowing down
one branch of a parallel circuit, and
6A flowing down another - what
would that tell you?
What are the rules for potential
difference in:
(a) a series circuit
(b) a parallel circuit
Sketch the current-potential difference graph for:
(a) a resistor
(b) a resistor with a higher resistance than (a)
(c) a filament lamp
(d) a diode
Explain how a diode works
Explain why the graph of a filament
lamp is a curve
The current-voltage graph of
a resistor is a straight line
through the origin -
what does this tell you?
What is an LED? How does it work?
Why are LEDs better than filament lamps?
What are CFLs? Why are they
better than filament lamps?
What is the difference between ac and dc?
What is the frequency of UK mains electricity?
Sketch a quick diagram to
show the correct wiring of a
plug (with the colours labelled)
Why are wires made of copper?
Why are plug pins made of brass?
Why are wires covered in plastic?
What is a fuse?
How do the earth wire and fuse
work together?

What does double-insulated mean?
Why does a double-insulated device
not need an earth wire?
How does an RCCB work?
Why is an RCCB better than a fuse?
What equations would you use to
calculate the electrical power of something?
What is charge measured in?
What is another name for
potential difference?
You should always choose a fuse
that is a little bit higher than the
current the appliance needs...why?
What is the relationship between
current and thickness of wire?
What is the difference between two
core and three core cable?
Compare the mass and charge of
a proton, neutron and electron
What is an isotope?
What does this mass number
and atomic number tell you?
Ra
226
88
Sketch a labelled diagram of the
plum pudding model
(a) What were the results of Rutherford's
experiment?
(b) EXPLAIN what the results of his experiment
told him about the structure of the atom
What would be needed for a new scientific model to be accepted?
What is:
(a) an alpha particle
(b) a beta particle
(c) gamma
What are the sources of background radiation?
Why do some people
What are the differences in these properties
of alpha, beta and gamma:
(a) their ionising power
(b) their range in air
(c) the penetration through different materials
(d) the effect of magnetic or electric fields
Why do beta particles curve more
and in the opposite direction to
alpha particles in an electric field?
What does deflection mean?
How does decaying by alpha affect the nucleus?
How does decaying by beta affect the nucleus?
Write down an example decay equation for alpha decay
Write down an example decay
equation for beta decay
What is half-life?
What two things do you need to know
when picking a radioactive source for a
particular job?
How is radioactivity used in a smoke detector?
How is radioactivity used in thickness control of foil?
How is radioactivity used as a medical tracer?
How is radioactivity used to find the leak in a water pipe?
How is radioactivity used in cancer treatment?
How is radioactivity used to sterilise medical equipment or make soft fruit last longer?
How is radioactivity used in carbon dating?

Which radioactive sources are the most dangerous
(a) inside the body
(b) outside the body
What is fission?
Where does fission take place?
Name two fissionable substances
Sketch a diagram of the chain reaction
What is fusion?
Where does fusion take place?
Describe in detail the life
cycle of a small star
Describe in detail the life
cycle of a large star
What does the presence
of gold on Earth tell us about
the formation of our Solar System?
Always select a fuse with a current rating slightly higher than the appliance needs
extra electron