Physics Paper 1: Triple Name ……………………………….. 1. Energy stores and transfers 2. Conservation of Energy 3. Efficiency 4. Energy Resources 5. Advantages and Disadvantages of Energy Resources 6. Electrical Circuits 7. Electrical Components 8. Sensing Circuits 9. Electricity in the Home 10. Electrical Power and Charge 11. Isotopes and Nuclear Radiation 12. Particle Model 13. Particles in Gases 14. Maths in Science 15. Rearranging Equations 16. Equations 17. Required Practicals Specific Heat Capacity Thermal Insulation Density Resistance V- I Characteristics
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Physics Paper 1: Triple
Name ………………………………..
1. Energy stores and transfers
2. Conservation of Energy
3. Efficiency
4. Energy Resources
5. Advantages and Disadvantages of Energy Resources
6. Electrical Circuits
7. Electrical Components
8. Sensing Circuits
9. Electricity in the Home
10. Electrical Power and Charge
11. Isotopes and Nuclear Radiation
12. Particle Model
13. Particles in Gases
14. Maths in Science
15. Rearranging Equations
16. Equations
17. Required Practicals
Specific Heat Capacity
Thermal Insulation
Density
Resistance
V- I Characteristics
1. Energy stores and transfers Energy Stores
Chemical
Magnetic
Electrostatic
Nuclear
Thermal
Kinetic
Gravitational potential
Elastic potential
Energy Transfer
Energy is transferred between energy stores:
When a system changes energy is transferred.
This can be into or away from the system, be-
tween objects in a system or between different en-
ergy stores.
A closed system is where neither matter nor ener-
gy enters or leaves. The total energy change in a
closed system is zero (energy is not created or
destroyed).
Mechanically (a force)
Electrically (moving charges)
Particles (Sound, heating - conduction)
Radiation (light or sound)
Kinetic Store
All moving objects have energy in the kinetic
store.
The more mass an object has the more KE it
has.
The faster an object is going the more KE it has.
Ek = 1/2 mv2
Eg. A car has a mass of 3000kg is travelling at
20m/s. Calculate the energy in the KE store.
Ek = ½ x 3000 x 202 = 600 000 J
Energy Transfer by Doing Work
Throwing a ball upwards: Force from a per-
son does work – energy is transferred from the
chemical store of the person to the kinetic store
of the ball.
A ball is dropped: Energy is transferred from
the gravitational store to the kinetic store. The
gravitational force does work.
A car braking to slow down: The friction on
the brakes does work. Energy is transferred
from the cars kinetic store to the thermal store
of the surroundings.
Energy Transfer by Heating (eg.
kettle boiling)
1) The water is the system.
Energy is transferred by heating
to the waters thermal store.
2) A two object system (water and
heating element).
Energy is transferred to the ther-
mal store of the heating element
electrically. This is then trans-
ferred to the thermal store of the
water.
Elastic Potential Store
Stretching or squashing an objects
raises its elastic potential energy
store.
Calculates the elastic potential
energy of a spring if it has not ex-
ceeded its limit of proportionality.
Kinetic Energy
mass
mass
Conduction
This occurs in solid objects. When an object is heated, ther-
mal energy is transferred to the kinetic store of the particles.
This causes them to vibrate more and collide with other parti-
cles, so energy is transferred between the kinetic stores.
Convection
When particles are free to move (in a liquid and gas) an increase in their ki-
netic store causes them to move faster.
This means the space between the particles increases, so the density of the
area being heated decreases.
The warmer less dense region rises and the cooler, denser regions fall.
Specific Heat Capacity
A measure of the energy transferred to a thermal store of an object. It is the amount of energy needed to raise the temperature of 1kg sub-stance by 1°C. Different substances will need different amounts of energy to do this.
∆Θ= temperature change (°C)
c = specific heat capacity (J/kg°C)
∆E= change in thermal energy (J)
m = mass (kg)
Gravitational Potential Store
Is increased when objects are raised off the ground. The amount of energy depends on the mass and height of the object and strength of the
gravitational field it is in.
A falling object has energy transferred from its GPE store to a kinetic store.
If there is no air resistance the energy lost from the GPE store = energy gained in the KE store.
There is usually air resistance, so some energy will be transferred to other stores, such as the thermal store of the surroundings.
Ep = m x g x h
Gravitational field strength (N/kg)
Height
Mass (kg)
Gravitational Potential Energy (J)
E = m x c x Θ
2. Conservation of Energy Conservation of Energy
Energy can be transferred, stored or dissipated but never created or destroyed.
All energy is never transferred usefully. Some is always wasted (dissipated).
For example, energy is transferred electrically to a laptop but some is dissipat-
ed to the thermal store of the laptop.
Reducing Wasted Energy
Friction between two moving objects causes energy to
be dissipated to the thermal store. It can be reduced by
lubrication.
Insulation reduces energy transfer by heating. This is
useful in our homes to reduce heating costs:
Cavity wall insulation fills the air gap between the
inner and outer wall reducing heat loss by convec-
tion.
Loft insulation reduces heat loss by convection
Double-glazing creates an air gap between the two
panes of glass to reduce energy loss by conduction.
Draught excluders reduce energy loss by
convection when placed around windows and doors.
Reducing the temperature difference between
the inside and outside will also reduce energy transfer.
Power
This is the rate of doing work (per second) in Watts.
1 watt = 1 joule of energy transferred per second.
eg. calculate the power of a motor that uses 6000J of energy to lift an object for
20 seconds.
A more powerful device can transfer more energy in a given time, or, will trans-
fer the same amount of energy in a faster time.
For example, if we have two identical cars but one with a more powerful engine
race. The more powerful one will finish first – it will have transferred the same
amount of energy but in a quicker time.
P = E/t Power (W)
Energy (J)
Time (s)
3. Efficiency
Efficiency
An efficient device wastes less energy than a less efficient device. It can
be calculated as a decimal, or multiplied by 100 to give a percentage.
Eg. calculate the efficiency of a motor that has a power of 500W and
transfers 300W usefully.
Useful and wasted energy
Appliance Useful Energy Wasted Energy
Light bulb Light Heating the sur-
roundings
Hair Dryer Kinetic Energy of
the fan.
Heating of the air.
Sound of the motor.
Heating the hairdry-
er itself.
Electric Motor Kinetic Energy
Gravitational poten-
tial energy if lifting.
Heating motor and
surroundings.
Sound waves.
4. Energy Resources Non-renewable
These will run out one day. They are fossil fuels
(coal, oil and gas) or nuclear fuel (uranium and
plutonium). Fossil fuels are burned to provide
energy to produce electricity.
Renewable energy These will never run out.
They are being replaced at the same rate, or
faster, than they are being used up.
Uses for Heating
Non-renewables: Natural gas is the most
common fuel burned to heat water in our heating
systems. Coal can be burned in fireplaces.
Electric heaters usually use electricity produced
from a non-renewable source.
Renewables: Geothermal heat pumps can be
used to heat homes. Solar water heaters use
thermal energy from the sun to heat water. Bio-
fuels can also be used to produce heat for a
heating system.
Uses for Transport
Non-renewables: Petrol and diesel are made from oil and used to power vehicles
such as cars. Coal is used in steam trains to boil water to produce steam to power the
train.
Renewables: Some vehicles run on biofuels. Electric powered vehicles can be
powered by renewables, such as solar cells.
Limits of Using Renewables
- Costs lots of money to build new power plants. Fossil fuels are very cost effec-
tive. People would have to pay for new power plants through energy bills or taxes from
the government.
- Difficulty placing new power plants (they may spoil the landscape)
- Many are not reliable, such as wind power
- Improving reliability takes a lot of expensive research and takes a long time.
- Personal changes can be expensive. It is very costly to buy solar cells for your
house or a hybrid car
For these reasons we are dependent on non-renewable energy resources.
Bio-fuels
A renewable energy resource made from plants or animal dung. Are burned to produce
electricity.
Dependency on Fossil Fuels
Currently we depend on fossil fuels to meet energy demands:
- large increase in population size
- more appliances require electricity
Our electricity usage in the 21st century has decreased as appliance have be-
come more efficient.
Oil is used to produce petrol and diesel as fuels for vehicles. Gas is burned to
cook with and to produce heat in our homes.
We are trying to reduce our dependency on fossil fuels. By 2020 the UK aims
to produce 15% of energy from renewable resources.
People want more Renewable Energy
More people want to use energy produced by renewable
sources because they know:
- burning fossil fuels is damaging the environment
- it is better to learn to get by without renewables before
they run out
Governments have set targets for using renewables due to
pressure from other countries and the public. This puts
pressure on energy companies to make changes.
Electric and hybrid cars are becoming more popular.
5. Advantages and Disadvantages of Energy Resources Bio-fuels
Produced from plants or animal
dung. Are used in the same way as
fossil fuels – burned to produce
electricity or run vehicles.
Where plants are used they take in
CO2 through photosynthesis during
their lifetime. When burned this CO2
is released again so no net change
in the amount of CO2 in the atmos-
phere.
+ Carbon neutral (if plants are
grown at the same rate as being
burned).
+ Reliable as crops grow quickly
- High costs to refine the fuel
- Space for growing food taken up
- Forests cleared to make space –
decay and burned vegetation re-
lease CO2 and methane.
Wind Power
The blades turn a generator which produces electric-
ity.
+ No atmospheric pollution
+ No fuel costs and minimal running costs
+ No permanent damage to the landscape when
removed.
- Visual and noise pollution
- Cannot increase supply to match demand
- High initial costs
- Cannot generate electricity if there is too little wind
Hydro-electric Power
Water flows out of a dam through turbines,
producing electricity.
+ Can respond immediately to increased
demand
+ Reliable (except if there is a drought)
+ No fuel costs and minimal running costs
- Requires land to be flooded to create a
dam
- Loss of habitats
- Look unsightly when the reservoir dries
up
Tidal Barrages
A large dam built across an estuary that allows the water back out to sea at a controlled speed
through turbines.
+ No atmospheric pollution
+ No fuel costs and minimal running costs
- Visual pollution
- Difficulty providing access for boats
- Initial costs are high
Geothermal Power
Radioactive decay in the core heats rocks near the surface. This
can be used to generate electricity or heat buildings directly.
+ Reliable
+ No atmospheric pollution
- Few suitable locations (only possible in volcanic areas)
- High cost to build power station
Non-renewable
+ Reliable
+ Easy to increase supply to match demand
+ Fairly low fuel extraction costs
+ High energy output
- Running out
- Release CO2 which contributes to global warming
- Release SO2 which causes acid rain
- Coal mines spoil the landscape
- Oil spills
- Nuclear waste difficult to dispose of
Solar Cells
Generate electricity from sunlight.
+ No atmospheric pollution
+ In sunny countries they are reliable (during the day)
+ Useful for remote places not supplied by the national grid.
+ No fuel costs and minimal running costs
- Cannot increase supply to match demand
- High initial costs
Atmospheric pollution includes CO2 which contributes to global
warming and SO2 which causes acid rain.
6. Electrical Circuits Key terms
Current is the flow of electrical charge. Measured in Amps (A)
Ampere - The ampere is the standard unit of measure of electric current. It is sometimes written as Amp.
Potential difference is the force that pushes the charge around. Measured in volts (V).
Volt - The standard unit of measure for electric potential (voltage).
Resistance is something that slows down the flow of current. Measured in ohms (Ω).
Ohm - The standard unit of measure for resistance.
Resistor - A basic electronic component that prevents the flow of electric current.
Electric circuit - An electric circuit is a collection of electronic components connected by a conductive wire that allows for electric current to
flow.
Watt - The standard unit of measure used for electric power.
Series Circuits
Current is the same throughout
the circuit: I1 = I2 = …
Potential difference is shared
across the components: Vtotal = V1
+ V2 +…
Resistance adds up: Rtotal = R1 +
R2 + …
Parallel Circuits
Current is shared across the
components: Itotal = I1 + I2 +…
Potential difference is the same
across all components: V1 = V2 =…
Total resistance will fall if two or more
resistors are added in parallel.
7. Electrical Components Components
A V
Light Emitting
Diode (LED)
Ammeter
Voltmeter
Cell
Battery
Variable
Resistor
Closed
switch
Open
Switch
Filament Bulb
As the voltage increases the current increases.
This causes the filament to get hotter, meaning
the resistance increases. Therefore, as the
voltage continues to increase the current levels
off.
Resistor
At a constant temperature the current is
directly proportion to the voltage.
This means it obeys Ohm’s Law.
Diode
The current can only flow in one direc-
tion because a diode has a very high
resistance in the opposite direction.
8. Sensing Circuits
Sensing Circuits
The pd of the power supply is shared between the fixed resistor and the thermistor.
If the temperature increases then the resistance of the thermistor will decrease.
This means there will be a larger pd across the resistor and therefore the fan, which will go faster (fan and resistor
will always have the same pd as they are connected in parallel).
Connecting the component across the variable resistor (LDR or thermistor) will have the opposite effect.
When it is dark the resistance of the LDR will be low, meaning the pd across both the resistor and bulb will be high.
Therefore the bulb gets brighter as it gets darker.
An example with numbers:
9V
1V
8V
Low temperature = high resistance
of thermistor, so very low pd across
resistor. Only 1V also across fan so
it does not turn.
High temperature = low resistance of
thermistor, so high pd across resistor.
Also 7V across fan so it turns.
2V
7V
9V
Light Dependent Resistor (LDR)
Thermistor
As the light intensity increases the
resistance drops. This means more
current can flow.
Can be used in automatic night
lighting and outdoor security lights.
As the temperature increases the
resistance drops. This means
more current can flow.
Can be used as temperature de-
tectors, such as in car engines
and thermostats.
9. Electricity in the Home
AC
With alternating current (AC) the current constantly chang-
es direction. It is produced by an alternating voltage where
the positive and negative ends keep alternating.
The UK mains supply is AC at 230V. It has a frequency of
50Hz.
National Grid
A network of cables that connects power stations to con-
sumers.
A huge amount of power is needed. This is achieved with a
high pd but a low current. A high current would cause
the wires to heat up, wasting a lot of energy. It is cheaper
to increase the pd and keep the current low for a given
power output.
Meeting Demand
Power stations have to meet
the demand for electricity,
which varies during the day.
They usually run below maxi-
mum capacity so more elec-
tricity can be generated to meet
demand, such as during big
sporting events.
DC
With direct current (DC) the current always
flows in the same direction. Batteries pro-
duce a DC voltage.
Peak Potential
difference at
peak and trough
Live Wire
If you touch the live a large
pd is produced across your
body and the current flows
through you. This electric
shock can injure or kill
you.
A connection between the
live and earth creates a low
resistance path to earth
so a large current will flow.
This could cause a fire.
Electrical Wiring
Most electrical appliances are connected to
the mains with a three core cable (3 copper
wires coated in insulating plastic):
· Live (brown) – Provides the alternating
pd at 230V.
· Neutral (blue) – Completes the circuit
carrying the current out of the appliance
at 0V.
· Earth (green and yellow) – A safety fea-
ture. Prevents the appliance becoming
live if there is a fault so does not normally
carry a current. It is at 0V.
10. Electrical Power and Charge
Power
Energy in an electrical circuit is transferred by a moving charge. The
charge has to work against resistance, so work is done. Work done
is the same as energy transferred and depends upon power.
Appliances have a power rating, the maximum operating power.
An appliance with a lower power rating will be cheaper to run (less
energy transferred per second).
A higher power rating might not mean more energy is transferred
usefully. It could be less efficient than another appliance so only
transfer the same amount, or less, energy to useful stores.
E = Pt Time (s)
Power (W)
Energy
transferred (J)
Power Calculations
Power (W) depends upon the potential difference (V) and current (A):
Or, if the potential
difference is not known: P = IV P = I2R
Charge
Energy is supplied to the charge at a power source, ‘raising’ through a
potential.
Energy is given up by the charge at components as it falls through a
potential drop.
E = QV
Charge flow
(Coulombs, C)
Potential difference (V)
Energy (Joules, J)
11. Isotopes and Nuclear Radiation
Isotopes
Different forms of the same ele-
ment.
Isotopes of an element have the
same number of protons but a dif-
ferent number of neutrons:
All elements have isotopes but
there are only a few that are stable.
Others decay into other elements to
become more stable by giving out
radiation.
8 protons, 8 neutrons
8 protons, 10 neu-
Decay
Alpha decay causes the charge and
mass of the nucleus to decrease:
Beta decay causes the charge of the nu-
cleus to increase. When an electron is lost
a proton is changed into a neutron:
Gamma rays do not change the mass or
charge.
Uranium-238 → Thorium-234 + α particle
Carbon-14 → Nitrogen-14 + β particle
Half Life
The time taken for the number of radioactive nuclei in
an isotope to halve. Activity (the rate at which a
source decays) is measured in Becquerel’s Bq (1Bq
= 1 decay per second).
eg. if the initial activity of a sample is 320Bq what will
it be after two half-lives?
1 half life = 320 ÷ 2 = 160Bq
2 half lives = 160 ÷ 2 = 80Bq
As a % this is
(80 ÷ 320) x 100 = 25%
Finding half-life
from a graph:
- Mark where half
the activity level is.
- Find the corre-
sponding time
(1.8s in this exam-
ple)
Thomson carried out experiments and discovered the electron. This led him to suggest the plum pudding model of the atom. In this
model, the atom is a ball of positive charge with negative electrons embedded in it.
Rutherford showed that plum pudding model was wrong. Positively charged alpha particles were fired at thin gold foil. Most alpha parti-
cles went straight through the foil. But a few were scattered in different directions by. It showed that the mass of an atom was in the centre
(the nucleus) and the nucleus was positively charged. This was called the nuclear model.
Bohr suggested that electrons orbit the nucleus at specific distances in shells
Chadwick provided the evidence for neutrons, about 20 years after the nucleus was an accepted idea. This provided evidence for
isotopes.
Radioactive Decay
Type of particle Properties How ionising Uses
Alpha
α
alpha particle – two
protons and two
neutrons (helium
nuclei).
Can only travel a few cm in
air and are absorbed by a
sheet of paper.
Very Smoke alarms. The α-particles
ionises air particles, causing a
current to flow. Smoke will
bind to the ions, stopping the
current so the alarm sounds.
Beta
β
A fast moving elec-
tron.
Have no mass and a
charge of -1. Travel a few
meters in air and are ab-
sorbed by about 5mm of
aluminium.
Moderate Testing thickness of sheets of
metal.
Gamma
γ
Are electromagnetic
waves.
Usually pass through ma-
terials. Absorbed by thick
sheets of lead or several
meters of concrete.
Weakly See EM waves sheet.
12. Particle Model
Solids
Have strong forces between particles, holding
them close together in a fixed, regular arrange-
ment. The particles can only vibrate around
fixed positions.
Liquids
Have weaker forces between particles so alt-
hough the particles are close together they can
move over each other at low speeds in ran-
dom directions.
Gases
Have almost no forces between particles. Have
more energy and are free to move in random
directions and speeds.
Internal Energy – the energy stored by the particles in a sys-
tem
Heating a system increases the energy particles have in their
kinetic and potential energy stores.
A temperature change depends on the mass of substance,
what it is made from and the energy input (see specific heat
capacity). If the substance is heated enough particles can
have enough energy in their kinetic stores to break bonds
holding them together and so a change in state occurs.
Density
Measures how compact a substance is. Depends on the material and how
the particles are arranged.
Compressing a less dense material pushes the particles closer together.
The mass would not change (same number of particles) but the volume
would.
Density (kg/m
3)
Volume (m
3)
Mass (kg)
Specific Latent Heat – the energy needed to change the state of 1kg of a
substance
Bonds are formed, giving out en-ergy. Internal energy decreases but the temp. doesn’t until all the substance has changed state.
Bonds are broken, taking in en-
ergy. Internal energy increases
but the temp. doesn’t until all
the substance has changed
state.
Specific latent heat of fusion = melting or freezing.
Specific latent heat of vaporisation = evaporating, boiling or condens-
ing.
Gas Pressure
When the particles in a gas collide with the side of the
container they exert a force on it.
The pressure is the force exerted per unit of area. In a
sealed container the gas pressure is the total force of
all the particles on the area of the container walls.
Increasing the temperature increases pressure be-
cause particles have a larger kinetic energy store. This
means they move faster so collide with the sides more
often and with more momentum = a larger total force
exerted so increased pressure.
13. Particles in Gases Temperature
Energy is transferred to the kinetic stores of particles when the temperature is in-
creased.
The higher the temperature the higher the average energy of the particles. This
means the higher the energy the faster the particles move.
Work Done
Work is done when energy is transferred by applying a force.
Work done on a gas increases its internal energy. This can increase the tempera-
ture of the gas.
Pumping up a bike tyre does work mechanically. The gas exerts a force on the
plunger (due to pressure). To push the plunger down against this force work has
to be done. Energy is transferred to the kinetic stores of the gas particles, increas-
ing the temperature.
Pressure
For a sealed container the gas pressure is the total force of
all the particles per unit of area. Increasing the temperature
of the gas means particles have more energy so collide with
the sides of the container with more force. Therefore the gas
pressure is higher.
Decreasing the volume means particles are closer together
so hit the sides more often. Therefore the gas pressure is
higher.
Pressure (p) and volume (V) are inversely proportional (if
one increases the other decreases):
Volume
Gas pressure causes an outwards force at right angles to the wall of the
container.
The pressure of the air pushes on the outside of the container.
A change in pressure can cause a container to change shape. Eg. if a heli-
um balloon is released it rises. As it gets higher the atmospheric pressure
decreases, causing the balloon to expand until the pressure inside the bal-
loon equals the air. pressure again.
Balloon at ground
level. Internal and
external pressures are equal.
Balloon rising. Air pres-
sure decreases. Internal
pressure is greater so
balloon expands
14. Maths in Science
15. Rearranging equations
Example 1. Power = Energy/Time or P = E / t
Rearrange to make energy “E”, the subject.
In order to change the subject of, or rearrange, a formula items in the formula need to be arranged so a different variable is the subject. We
have to use inverse operations for example dividing is the inverse of multiplying.
Here are two examples of rearranging equations:
Example 2
v = u + at
Rearrange to make initial velocity “u”, the subject.
V = u + at
V-at = u + at –at
U = v-at Or V-at = u
P = E
Multiply both sides by t
P x t = E
the t’s cancel out
E = P x t Or P x t = E
t
t
P x t = E
t
x t
x t
The subject of a formula is the variable that is being worked out. It can be recognised as the letter on its own on one side of the equals sign.
For example, in Maths the formula for the area of a rectangle A = bh (area = base x height), the subject of the formula is A.
16. Equations
The
se a
re t
he
ph
ysic
s e
qu
atio
ns
you
ne
ed t
o le
arn
off
by
he
art
for
GC
SE P
hys
ics.
W
ord
s
Sym
bo
ls
1
we
igh
t =
ma
ss ×
gra
vita
tio
na
l field
str
en
gth
W
= m
g
2
wo
rk d
on
e =
fo
rce ×
dis
tan
ce (
alo
ng t
he
lin
e o
f a
ctio
n o
f th
e fo
rce)
W =
Fs
3
forc
e a
pp
lied t
o a
sp
ring =
sp
rin
g c
on
sta
nt
× e
xte
nsio
n
F =
ke
4
mom
en
t of
a fo
rce =
forc
e ×
dis
tan
ce
(n
orm
al to
dire
ction
of fo
rce)
M =
Fd
5
pre
ssu
re =
fo
rce n
orm
al to
a s
urf
ace
/ a
rea o
f th
at su
rfa
ce
p
= F
/A
6
dis
tan
ce
tra
ve
lled
= s
pe
ed
× tim
e
s =
vt
7
acce
lera
tion
= c
ha
nge
in v
elo
city /
tim
e t
ake
n
a =
Δv/t
8
resu
lta
nt fo
rce =
ma
ss ×
acce
lera
tion
F
= m
a
9
HT
mom
en
tum
= m
ass ×
ve
locity
p =
m v
10
kin
etic e
ne
rgy =
0.5
× m
ass ×
(spe
ed
)2
Ek =
0.5
mv 2
11
gra
vita
tio
na
l po
ten
tia
l e
ne
rgy =
ma
ss ×
gra
vita
tio
na
l field
str
en
gth
× h
eig
ht
Ep =
mg
h
12
p
ow
er
= e
ne
rgy t
ran
sfe
rre
d /
tim
e
P =
Et
13
p
ow
er
= w
ork
do
ne
/tim
e
P =
W/t
14
eff
icie
ncy =
usefu
l o
utp
ut
en
erg
y t
ran
sfe
rre
d /
usefu
l in
pu
t e
ne
rgy t
ran
sfe
rre
d
15
eff
icie
ncy =
usefu
l p
ow
er
ou
tpu
t /
tota
l po
we
r o
utp
ut
16
w
ave
sp
ee
d =
fre
qu
ency ×
wa
ve
len
gth
v =
fλ
17
ch
arg
e f
low
= c
urr
en
t ×
tim
e
Q =
It
18
p
ote
ntia
l d
iffe
ren
ce
= c
urr
en
t ×
re
sis
tan
ce
V
= I
R
19
p
ow
er
= p
ote
ntia
l d
iffe
ren
ce
× c
urr
en
t P
= V
I
20
p
ow
er
= (
cu
rre
nt)
2 ×
re
sis
tan
ce
P
= I
2R
21
e
ne
rgy t
ran
sfe
rre
d =
po
we
r ×
tim
e
E =
Pt
22
e
ne
rgy t
ran
sfe
rre
d =
ch
arg
e f
low
× p
ote
ntia
l d
iffe
ren
ce
E
= Q
V
23
d
en
sity =
ma
ss / v
olu
me
ρ
= m
/v
Gra
vita
tio
na
l field
str
ength
, g (
= 9
.8N
/kg),
will
alw
ays b
e g
ive
n in
th
e q
ue
stio
n.
17. Required Practicals
Specific Heat Capacity
Method
1. Measure and record the mass of the copper block in kg.
2. Place a heater in the larger hole in the block.
3. Connect the ammeter, power pack and heater in series.
4. Connect the voltmeter across the power pack in parallel.
5. Put the thermometer in this hole.
6. Switch the power pack to 12 V. Switch it on.
7. Record the ammeter and voltmeter readings. These shouldn’t change during the experiment.
8. Measure the temperature and switch on the stop clock.
9. Record the temperature every minute for 10 minutes (600 seconds).
10. Calculate the power of the heater in watts.
To do this, multiply the ammeter reading by the voltmeter reading.
11. Calculate the work done by the heater. To do this, multiply the time in seconds by the power of the heater.
12. Plot a graph of temperature in 0C against work done in J and draw a line of best fit. Take care as the beginning of the graph may be
curved.
The specific heat capacity is the heat capacity divided by the
mass of the block in kg.
IV— Work done
DV—temperature
CV—metal block
Voltmeter must
be connected in
parallel
Possible Errors
Heat is lost to the surroundings
Part of the emersion heater is outside the block
Thermometer is measuring the temperature of water and not the block
Thermal Insulation
IV – Time (s)
DV – Temperature Change
CV – Volume of water, material of insulation, starting temperature.
Method
1. Use the kettle to boil water. Put 200 ml of this hot water into a 250 ml beaker.
2. Use a piece of cardboard as a lid for the beaker. The cardboard must have a hole for
the thermometer.
3. Insert the thermometer through the hole in the cardboard lid so that its bulb is in the hot water.
4. Record the temperature of the water and start the stopwatch.
5. Record the temperature of the water every 5 minutes for 20 minutes.
6. Repeat steps 1‒5 using one or more layers of insulating material wrapped around the beaker.