all of paper 1 Flashcards
(123 cards)
1
Q
Energy is transformed from the CPV through the metal base of the cooling unit. Explain how the process occurs
A
When metal heated, delocalized electrons
gain kinetic energy and move quicker
transfer kinetic energy to other electrons
when they collide with them.
2
Q
Stage 2 features that could help the metal cooling transfer energy quicker
A
Larger surface area black paint.
(black is a good emitter of IR radiation)
3
Q
The speed of entry of the water is greater than, equal or less than when it leaves the water.
A
Same speed,
loss of gravitational potential, energy transfer to kinetic energy
4
Q
Water moving turns the turbine to produce electricity. Describe the energy transfers taking place in the system.
A
Stored water has energy in its gravitational potential energy.
Energy transferred mechanically.
Transferred to the kinetic store of the water as it flows through the tunnel
Energy transferred to the kinetic store of the turbine as it turns.
5
Q
why is stand by not good
A
uses electricity
generating electricity produces CO2
CO2 contributes to global warming
6
Q
Describe how electricity is generated in a hydroelectric power station
A
-water moves from high to low level
-transferring GPE to KE
-rotating turbine to turn generator
-transferring KE to ELECTRICAL energy
7
Q
shale gas
A
Low CO2 emissions
free - Only cost is the extraction.
Digging destroys habitats. Extracting shale gas involves digging underground- expensive. Extraction releases CO2.
8
Q
Nuclear fission.
A
Reliable, no CO2 emissions, high energy density fuel, longer operating life
radioactive waste, accidents at nuclear stations , longer start up time, high building costs
9
Q
Control roads and nuclear fission.
A
Chain reactions occur.
Neutrons are released, control rods absorb.
Neutrons can be moved up and down
to increase or decrease rate of chain reactions.
10
Q
What would happen if the reaction were to continue?
A
Uncontrolled chain reaction.
Number of neutrons released increases exponentially.
nuclear explosion.
11
Q
Nuclear power as an energy source.
A
Reliable produces no greenhouse gases.
Radioactive waste dangerous to dispose of.
A small amount of nuclear fuel generates a large amount of electricity.
12
Q
How does the shape of the graph show the filament lamp is known on the conductor?
A
As potential difference increases, current increases.
the current increase decreases because
Temperature of the filament bulb increases as current increases. So resistance increases causing current to decrease.
13
Q
2 improvements Measuring resistance of LDR.
wait time before each light intensity.
Digital Ammeter
A
underground cables
cannot be seen
not a hazard to aircrafts
not likely to be damaged
reduced shock hazard
14
Q
Shape of the graph shows that the LDR is no normal conductor.
A
The graph is a curve, so not directly proportional.
15
Q
Describe the difference between conventional current and electron flow
A
Electron current is the flow of electrons in a circuit.
Electrons have negative charge so they float towards positive terminal.
Conventional currents is the reversed movement of positive charge.
Moves towards the negative terminal.
16
Q
On a current against potential difference graph
A
the smaller the gradient
the greater the resistance
Because Lower value for currents for all values of potential difference.
17
Q
Benefit of connecting the heating elements in parallel.
A
Current will flow More
because the total resistance in circuit is lower.
More energy transferred.
Because potential difference is not shared between elements. As in series.
(elements can be turned on and off - because a switch can be placed on each branch.)
18
Q
graph of Mean total resistance against the number of resistors in parallel. what does it tell you
A
As the number of resistors in parallel increases, the resistance decreases. The relationship is inversely proportional.
19
Q
Explain how an object with no charge may become positively charged
A
Negative charged electrons.
electrons transferred
Away from the object.
20
Q
explain why the students hair stands on end when the generator is switched on
A
Each head gained the same type of charge.
Same charge as repel.
Why does friction cause child to become charged?
Electron transfer from trampoline to child
21
Q
Why does copper wire prevent shock?
A
Good conductor.
So low buildup of charge. ( or smaller potential difference.)
22
Q
When the youth stops jumping, he touches the metal side of trampoline. Explain why he receives an electric shock.
A
There’s a potential difference between child on trampoline.
Electrons transfer from child to trampoline.
the charge is earthed
23
Q
What can you tell about the charge on the child if the slide were made from metal?
A
Child wouldn’t receive any charge.
Charge will pass through the metal to earth.
24
Q
Explain why the reading on the balance decreases
A
Road attract.
Upwards force
25
When the student brings the two rows closer together, the reading decreases further.
The attraction force increases
as the distance between the charges decreases.
26
Explain what happens as the roads were rubbed with the clothes
electrons Move between the cloth and rod.
Where electrons gather becomes negative.
Where electrons move away from becomes positive.
27
Arrangements and motion of solid.
Regular pattern vibrate in fixed positions, closely packed.
28
Liquid
Irregular pattern, flow over each other, closely packed.
29
Stay and explain the variables needed to calculate specific capacity of water.
Mass of water. Change in temperature. Energy from heater.
Measure temperature at the start and at the end
measure the mass of the anti cup and mass of the cup plus the water.
Zero scale with empty cup before adding H2O.
Use start and end readings on joulmeter.
30
Calculation of specific latent heat using the method may give a value that is different to the true answer. Explain why.
Energy may have been lost from water bath to surroundings.
This would increase energy.
Since energy is directly proportional to latent heat, this would increase the value of specific latent heat.
31
Expands its temperature decreases. Explain how this affects the pressure of the gas.
Pressure decreases,
molecules slowdown.
The collisions with container walls are less frequent.
There is a smaller force.
32
Some of the gas molecules dissolve into the cream. Suggest how this affects the pressure of the gas and the space above the cream.
Pressure decreases.
There are fewer molecules colliding with the walls.
Smaller force from molecules.
33
Explain how gas particles produce pressure on the walls of the spray can.
Particles collide with the wall.
Continuously hitting the wall. Producing a force.
Pressure =force / area.
34
Explain what happens to the gas pressure in the spray can as the liquid leaves.
Gas pressure decreases.
Gas molecules stay constant.
Gas volume increases.
Inversely proportional to volume.(pv=constant)
Particles collide with the wall less frequently.
35
why is the cool balloon is much smaller than the warmer one.
Particles move at a lower speed so less kinetic energy
On average.
Particles hit the size of container less frequently with less energy.
Reduces the pressure.
Tension in balloon pulls balloon to smaller size.
36
Investigate link between temperature and size of balloon. Identify 3. Possible faults and suggest improvements?
diff time in freezer does not give range of temperatures
Improve by using a water bath set to a range of temperatures.
Measure size is too vague.
measure volume, length, diameter, circumference.
Difficult to measure size with a ruler.
Measure the volume of water dissipated.
Repetitions do not make it a fair test.
Control variables.
Balloon may warm up. So take measurements quickly.
37
Alpha particle scattering experiment.
Environment.
A vacuum. Because alpha particles absorbed by short distances in air.
38
Explain readings of alpha scattering experiment
Small proportion deflected at large angles.
Shows that the mass and charge are concentrated in the nucleus.
Majority went straight through.
Most of atom is empty space.
Charge of the nucleus.
Positive because the alpha particle is positive and repelled at an angle
39
What is excitation?
Electrons gain enough energy to move up an energy level.
Hasn't left the atom.
40
What is ionization?
Removal or addition of electron when given energy.
41
Explain how scientists can use radioactivity to find the age of a piece of granite. (4)
There is a known activity when rocks are formed.
Scientists can measure the activity now.
Activity can be compared with the original activity.
Scientists can determine the The number of half lives that have gone.
Calculate the age of granite through knowledge of half life.
42
Suggest why the age of a piece of granite could not be found using a uranium isotope with a half life of 15 hours.
Half life is short.
Age cannot be determined because the uranium would have already decayed.(would be too small to distinguish from background radiation.)
43
Isotope.
Same number of protons but different number of neutrons.
They do not emit radiation.
44
Describe what happens the number of protons and neutrons of 210Pb decays to 210Bi
A neutron has become a proton in this decay.
Proton number increase by 1.
Neutral number decreased by 1.
Beta decay.
45
Why does the mass and atomic number not change when a gamma is emitted?
Gamma is not a particle,
has no mass, no protons or neutrons,
so no particles lost when gamma ray is emitted.
Gamma is electromagnetic radiation.
46
How Much does the number of a particle reduce after two half lives
2^2 = so reduced by 4
47
Pro and con of peer reviewed research
Findings from experiments are looked over by other scientists.
Other scientists can learn from findings.
and check for accuracy
48
Injection solution of technetium 99 radioactive isotope detector attack. Patient has a short half life. Explain why isotopes that emit alpha particles or beta particles are not suitable for this.
Not enough penetration range.
Would be absorbed by air.
So more likely to cause cancer and themselves.
49
Suitable half life to use for radioactive tracer?
Long enough to carry out procedure.
Short enough to not 'cause any long term damage.
50
Long enough to carry out procedure.
Short enough to not 'cause any long term damage.
Range of alpha radiation is slow.
Radon is a gas so the particles are mobile.
Americium particles stay in place.
Radon can be inhaled. But americium stays in the smoke detector.
51
Explain why the risk of health from rate on gas is low.
Raven has a short half life. so Gas will quickly lose its radioactivity.
52
Man made background radiation. Medical sources Nuclear.
Background radiation. Food rocks. Sun rate on gas.
53
Method that should be used to correct for background radiation.
Remove radioactive source.
Measure background count rate,
repeat reading and calculate average.
Subtract this value from the experiment values
54
ontrol variables of background radiation experiment.
Size of sample, same material, distance from detector.
55
Suggest properties of isotope in order to be used as a medical tracer
.
Able to penetrate out of body.
Long enough half life to move around body before decay.
Sure enough, half life that I won't remain in body and damage cells.
Non-toxic.
(able to be detected from outside body)
56
Describe the process of nuclear fission
Fuel roads made of uranium.
Nucleus of uranium absorbs 1 neutron.
57
Nucleus splits because it is unstable
Into two smaller nuclei and releases 2 to 3 neutrons and gamma radiation.
The energy released is transformed into kinetic energy store of the fission products.- or the mass converted to energy
58
Explain how a chain reaction occurs in the reactor.
Uranium nucleus absorbs the neutron.
Nucleus splits.
Releasing neutrons.
59
Explain how this leads to a chain reaction.
Nucleus splits.
Releasing neutrons.
Neutron collides with uranium nuclei.
60
Explain the energy transfer in a nuclear reactor.
Energy transformed from nuclear energy Store of the uranium nucleus
To the kinetic energy store of the neutrons and the daughter nuclei.
61
explain what is Meant by fission products.
Particles formed after fission.
Neutrons and daughter nuclei.
62
Explain what is why it is important to contain these fission products for such a long time.
Products are radioactive.
Product emit Ionizing radiation.
Last for a long time.
63
gamma
Electromagnetic wave.
Most penetrating.
Least ionizing.
Largest range in air.
Travel very large distances.
No charge.
64
alpha
2 protons, 2 neutrons.
Least penetrating.
Stopped by paper and skin.
Shortest range in air.
Travels few centimeters in air.
Most ionizing.
+2 charge.
65
beta
Fast moving electron emitted from nucleus.
Medium penetration.
Stopped by thin sheet of aluminum.
Short range in air 1m.
-1 Charge.
66
National Grid No economical
Long cables are needed. Energy dissipated
67
Hydroelectricity.
Constant output. Low installation costs. Low power output.
Renewable. No fuel cost. No CO2 produced. Low running cost.
Difficult to set up. Damage wildlife. Noisy. Visual pollution
68
wind turbines
Higher average power output.
Renewable. No fuel cost. Low running cost. No CO2 produced.
High cost. Unreliable. Kills birds.
69
Why is speed at the bottom of the slide much less than calculated?
Work is done against friction due to the slight not being smooth.
Kinetic energy transfer to surroundings
70
Halogen bulbs to LED bulbs would reduce the cost of running growth cabinet. Why?
Input power is less.
Produce less waste energy.
Increases temperature.
So cooler on for less time.
71
Nuclear power.
Lots of energy produced from small mass.
Reliable.
No pollutant gases. Small volume wasted.
But leak into the ground.
Get into food chain.
Radioactive waste.
72
Biofuels
Carbon neutral.
More land use.
More jobs? More profit
73
How do Earth and the fuse protect?
Electricity flows to Earth.
Blow the fuse.
Break the life circuit.
Stops electricity flowing.
74
why does resistance of lamp increases as potential difference increases.
Metals have free electrons.
As temperature increases. ions vibrate more.
Electrons collide more with ions.
75
Thermistor.
Temp increases. > resistance decreases.> current increases. > potential difference decreases.
76
LDR
As light increases. Resistance decreases. Current increases.
Uses: light sensing circuits
77
If a negative charge is placed in an electric field, in which direction does it feel force?
A negative charge feels force in the opposite direction of the field lines.
78
The arrow on an electric field diagram shows
the direction a positive charge would be pushed
79
What causes sparks
2 charged objects
In an electric field
Large potential difference between the two
Causing electrons to be knocked out of atoms
And move through the air
80
Explain why transferring the electricity directly to local homes is more efficient
than using the National Grid to distribute the electricity
less energy lost
because cables are shorter
81
How is the National Grid designed to reduce energy losses during
transmission?
step up transformers increase p.d
reduce current
increase efficiency
by reducing energy lost through heat
82
Explain the advantages of using energy from nuclear fuels to generate electricity
rather than using energy from the wind.
concentrated source of energy
able to generate continuously
the energy from nuclear fission
is used to heat water to steam to turn turbine linked to a generator
83
Give one reason why the householder should stay connected to the National
Grid.
sometimes demand is greater
84
reduce co2 emissions
reduce use of fossil fuelled power stations
use more nuclear power
renewable energy sources
make power stations more efficient
85
temperature sensor and data logger instead of
a glass thermometer to measure temperature.
greater sensitivity
data analysis
could take more frequent reading
reduces instrument reading error
86
Explain why the insulation recommended by the student will reduce the heat
transfer from the Sun to the glacier.
foil is a poor absorber of thermal radiation (good reflector)
foam traps air which is a (good) insulator
87
Explain, in terms of particles, how heat is transferred through the glass wall of a
boiling tube.
particles vibrate faster with more kinetic energy
energy transferred by collisions with other particles
88
Heat transfers:
heat = radiation
convection = liquids
conduction = solids
Explain, in terms of particles, how evaporation causes the cooling of water(4)
the fastest particles have enough energy
to escape from the surface of the water
therefore the mean energy of the remaining particles decreases
the lower the mean energy of particles the lower the temperature (
In each test, the water cooled faster during the first five minutes than during
the last five minutes. Why?
bigger temperature difference (between the water and surroundings)at the
start (than at the end)
89
The student’s results can only be used as an estimate of the mean power at her
location.
energy used to heat metal pan (as well as the water)
* energy transfer to the surroundings (through the insulation)
* angle of solar radiation will have changed during investigation
* intensity of solar radiation may have varied during investigation
90
dark matt > reach room temp fastest > best absorber of infrared r
small surface are > reduces energy transfer
control variables
same area / shape of can
* surrounding temperature is the same for all cans
* same surface underneath cans
* same position in the room
91
Describe how the design of a vacuum flask keeps the liquid inside hot.
plastic cap:
* plastic is a poor conductor
accept insulator for poor conductor
* stops convection currents forming at the top of the flask so stopping
energy transfer by convection
* molecules / particles evaporating from the (hot) liquid cannot move into
the (surrounding) air so stops energy transfer by evaporation
* plastic cap reduces / stops energy transfer by conduction / convection
evaporation
glass container:
* glass is a poor conductor so reducing energy transfer by conduction
* glass reduces / stops energy transfer by conduction
vacuum:
* both conduction and convection require a medium / particle
* so stops energy transfer between the two walls by conduction and
convection
* vacuum stops energy transfer by conduction / convection
silvered surfaces:
* silvered surfaces reflect infrared radiation
accept heat for infrared
* silvered surfaces are poor emitters of infrared radiation
* infrared radiation (partly) reflected back (towards hot liquid)
* silvered surfaces reduce / stop energy transfer by radiation
92
solar cells to generate this electricity.
source is renewable
* conserves fossil fuel stocks
* can be used in remote areas
* do not need to connect to the National Grid
benefit of developing brighter and more efficient LED chips.
price of LED bulbs will drop
less electricity needs to be generated
less CO2 produced
less energy wasted
93
why is matt black good for a fire place
black is a good emitter of infrared radiation (heat)
(black is a good absorber but no mark)
large surface area
matt surfaces are better emitters than silver surfaces (the shinier and lighter the surface the more it reflects)
wood rather than fossil fuels
renewable
carbon neutral
conserves fossil fuels
94
A student used the apparatus drawn below to investigate the heating effect of an
electric heater. Explain a method to carry this out. INSULATION PRACTICAL but without the layers)
-pace metal block on a heat-proof matt
- immerse an immersion heater in the larger hole of the metal block
-use a pipette to pour water into the smaller hole of the block and place thermometer in the water
-connect immersion heater to a power supply ( joulemeter)
-place stopwatch near apparatus
- record initial temperature of the thermometer before power supply switched on
-switch the power supply on and the stopwatch
-record the temperature in fixed intervals
-turn off power supply let block cool and repeat experiment to calculate mean
-plot graph of temperature against time
risk assessment
-metal block gets hot > can burn skin > don't touch
-wire can get hot > electric shock >turn power off before touching
increase accuracy
-use digital thermometer
-ensure good thermal contact by adding thermal paste between block and heater
-take smaller interval reading
-insulate metal block to reduce heat loss to surroundings
-take more readings and calculate mean
95
Heating effect of an electric heater experiment.
energy increase of block is lower than expected. why
-energy transferred/lost to surrounding
-some energy used to warm the heater
-metal block is not insulated
specific heat capacity of a metal is low > will heat up the most > less energy needed to raise temperature by 1 degree Celsius
96
Explain why the speed of the bullet decreases so quickly.
friction / air resistance is high when speed is high
Energy is much greater than the kinetic energy of the bullet and block just after the
impact. What has happened to the rest of the energy
transferred to heat and sound
97
The miners working in a salt mine use smooth wooden slides to move quickly from one level to another. The speed of the miner at the bottom of the slide is much less than the calculated
maximum possible speed. Explain why
-work is done
-against friction between miner and slide
-due to the slide not being smooth
-causing kinetic energy to be transferred as heat / to the internal energy of the surroundings
98
For the same braking force, explain what happens to the braking distance if the
speed doubles
* doubling speed increase the kinetic energy
* kinetic energy increases by a factor of 4
* work done (by brakes) to stop the car increases
* work done increases by a factor of 4
* work done is force × distance and braking force is constant
* so if work done increases by 4 then the braking distance must increase by 4
99
Circuit with battery, variable resistor, filament lamp, voltmeter, ammeter.Describe how the student could use her circuit to investigate how the current
through a filament lamp affects its resistance.
* ammeter used to measure current
* voltmeter used to measure potential difference
* resistance of variable resistor altered to change current in circuit or
change potential difference (across filament lamp)
* resistance (of filament lamp) calculated or R=V / I statement
* resistance calculated for a large enough range of different currents that
would allow a valid conclusion about the relationship to be made
100
Describe how a student would use the circuit to take the readings necessary to
determine the resistance of resistor R.
Explain why the student should open the switch after each reading.
-= resistor would get hot if current left on
so its resistance would increase
* switch on
* read both ammeter and voltmeter
* adjust variable resistor to change the current
* take further readings
* draw graph
* (of) V against I
* R = V / I
HOW DOES FUSE WORK(3)
-if current gets too high
- fuse melts
-and breaks circuit
101
State what happens to the total resistance of the circuit and the current through the
circuit when switch S is closed to create a parallel circuit
total resistance will decrease,
so current will increases
Suggest a reason for the anomalous result.
measurement of V too small
* measurement of I too big
* incorrect calculation of R
* thermometer misread
Describe an investigation a student could do to find how the resistance of a metal sample varies with temperature.
-Connect the metal sample to a power supply
-connect ammeter in series to measure the current.
-connect voltmeter in parallel with the metal sample to measure the voltage across it.
-Fill the beaker with water and place heat-proof surface
- Immerse the metal sample completely in the water
-place thermometer in water to measure temperature
* read V and I
* read temperature using the thermometer
* then apply heat using Bunsen burner
-Stir the water gently with a glass rod to ensure even temperature distribution.
* read V and I at least 3 different temperature
* determine R from V / I
* range of temperatures above 50 °C
* details of attaining 0 °C or 100 °C
* last reading taken while boiling
* graph of R against T
risk assessment
improve accuracy
- Use a digital thermometer for precise temperature readings.
- Stir the water continuously to ensure even temperature distribution.
-Take multiple readings of voltage and current for each temperature and average them.
-metal sample is fully submerged for uniform heating.
-Use an insulated beaker to reduce heat loss to the surroundings.
102
cons of thermometer vs liquid in glass thermometer
-not portable
-needs an electrical supply
* cannot be read directly
change current by
- adjusting variable resistor
-adding more cells (which will change p.d)
errors in measuring resistance of material
-measuring length incorrectly
-measuring current incorrectly
-ammeter / voltmeter incorrectly calibrated
-meter has zero error
103
variable resistor = used to obtain a range of values for p.d
as p.d increases > temperature increases > resistance increases
halogen vs LED bulb (6)
-halogen are cheaper to buy
simply giving cost figures is insufficient
* 6 halogen lamps cost the same as one LED
* LEDs last longer
* need to buy 18 / more halogen lamps to last the same time as one LED
* 18 halogens cost £35.10
* costs more to run a halogen than LED
* LED has lower maintenance cost
energy efficiency
* LED works using a smaller current
* LED wastes less energy
* LEDs are more efficient
* LED is 22% more energy efficient
* LED produces less heat
* LED requires smaller input
104
A student investigated how the force of attraction, between a coil and an iron rocker,
varies with the current in the coil.
-place iron rocker on the pivot,
-Connect the coil to a variable power supply and ammeter and variable resistor to vary and measure the current passing through it.
-coil is positioned close to one end of the rocker without touching it.
-Place known mass on the end of the rocker opposite the coil.
-Adjust the position of the pivot or add small weights to balance the rocker with no current
-Gradually increase the current in the coil using the variable power supply until the magnetic force balances the rocker
-Record the current required for balance.
-Replace the small mass with a different known mass.
-Record the current for each mass.
-F=m⋅g
-Plot a graph of magnetic force against current
risk
current gets too high > wire overheats> turn power supply off
masses can damage apparatus
improve accuracy
-use digital equipment to measure the current and small masses.
-Ensure the pivot point is frictionless to avoid resistance affecting the balance.
-Take multiple readings for each mass and average the results to minimize random errors.
-Use a fine adjustment on the power supply for gradual current changes. ( smaller intervals)
The magnetic force increase proportionally with the current, as per the relationship
𝐹∝𝐼
assuming the magnetic field strength remains constant.
= graph is straight line through origin
105
two extra components that must have been included in the circuit
-ammeter - to measure current
-variable resistor - to vary current
-switch - to stop apparatus getting too hot
-fuse- to break circuit if current is too big
changes that would allow lower values of current to be used in
this investigation.
-use smaller mass
* move mass closer to pivot
* reduce gap between coil and rocker
* more turns (on coil)coil / loop
* iron core in coil
I - V graph
- higher current for any p.d
- means higher power output
- bulb A will be brighter
use I-V graph to explain why bulb B has higher resistance
-lower current for same p.d
-lower gradient
(gradient is the resistance)
ohmic conductor in I - V graph
-current is directly proportional to potential difference (straight line through origin)
- so resistance is constant
ammeters must have low resistance
-to reduce effects of high current
106
A student plans to investigate how the resistance of a light-dependent resistor
(LDR) changes with light intensity.
(LAMP AND A LIGHT SENSOR)
-Connect the LDR to a circuit with an ammeter, voltmeter, and a variable resistor
-Use a light source (e.g., a lamp) and a ruler to measure the distance between the lamp and the LDR.
-Ensure the room is dark to minimize interference from other light sources.
-calculate intensity using
𝐼∝1/𝑑^2
-Adjust the distance of the light source from the LDR in intervals
-measure V and I at each distance
- V=IR
Method to Investigate Resistance of a Thermistor at Different Temperatures
(BUNSEN BURNER AND THERMOMETER)
-Connect the thermistor, ammeter in series, and voltmeter in parallel
-Place the thermistor in a beaker filled with water.
-Insert a thermometer into the water to measure its temperature.
-Use a Bunsen burner to heat the water slowly while stirring to ensure even heat distribution.
-Record the temperature of the water using the thermometer at regular intervals
-For each temperature reading, measure the current from the ammeter and the voltage from the voltmeter.
-V=IR calculate R for each temp.
-Repeat the experiment at least three times and take mean for each temp.
risk assessment
-hot water > burns
accuracy
-digital thermometer
-Use a water bath with an electric heater instead of a Bunsen burner.
-stir water
107
why 18 V battery could not be used as the input of a transformer.
batter is d.c
transformer needs a.c
108
If the electrician touches the live wire he will receive an electric shock.
Explain why.
potential of the live wire is 230 V
potential of the electrician is 0 V
large potential difference between live wire and electrician
current passes through his body
109
Explain how the householder is wasting money when filing kettle to top
bigger volume takes more time to heat up
so more energy transferred
this costs more money
110
What is meant by specific latent heat of fusion?
amount of energy required to change (the state of a substance) from
solid to liquid (with no change in temperature)
111
keeping the road clear of ice using:
* energy storage
* salt
* undersoil electrical heating.(6)
energy storage
PRO
* no fuel costs
* no environmental effects
CON
* expensive to set up and maintain
* need to dig deep under road
* dependent on weather
* digging up earth and disrupting habitats
salt spreading
PRO
* easily available
* cheap
CON
* can damage trees / plants / drinking water / cars
* needs to be cleaned away
undersoil heating
PRO
* not dependent on weather
* can be switched on and off
CON:
* costly
* bad for environment
112
How does the higher power rating affect the cost ?
more energy used per second
so cost is higher
113
Reducing the amount of energy used by washing machines could reduce the
amount of carbon dioxide emitted into the atmosphere.
Explain why.
-less electricity needed
-less power stations
-less fossil fuels burned
uses more power/energy > more electricity needed to be generated > more fossil fuels burned
114
Suggest how data collected and displayed by the electronic device could be useful to the homeowner.
-can look for patterns
-can reduce use
-reduce bills
-identify which appliance uses more energy
-replace appliances with more efficient ones
115
ceramic bricks are surrounded by 'super-efficient' insulation.
Explain why.
REDUCED ENERGY TRANSFER
SO KEEPING BRICKS HOT FOR LONGER
116
how do sparks happen
-large p.d / charge difference
-causing an electric field
-electrons removed from air particles
-air becomes a conductor
-current flows through it easily
117
how does electric shock happen
-A is rubbed against B,
- electron transfer from A to B
- so B is negatively charged and A is positively charged
- when person touches B the electrons are transferred to them --
- Compared to B person is positively charged so electrons jump across the gap between B and person
- creating a spark > electric shock
-electrons go through body into the earth.
-person is the ‘earthed’ object
118
how can static electricity be reduces/prevented
-use a conductor(metal)
-allows charge to flow through it
-earthing the charge
119
The resistance of the metal filament inside the bulb increases as the potential difference across the bulb increases.
Explain why.
-metal contains delocalised electrons AND IONS
-as temp increases IONS vibrate with higher amplitudes/faster
-IONS COLLIDE WITH ELECTRONS MORE FREQUENTLY
-
120
The air inside the fridge forms a convection current when the fridge door is closed. Explain why.
-air near compartment looses energy / is cooled
-cool air is dense so air particles closer together
-so cool air falls
-air is dissipated upwards
121
pro of more efficient appliances
-reduces emissions into atmosphere
* lower input power / uses less energy / wastes less energy
* costs less to run
-land fill
* energy waste in production
* cost or difficulty of disposal
* transport costs
122
Explain how rubbing an acetate rod with a cloth causes the rod and cloth to become
charge
-friction causes
* electrons (to) move
* from the acetate rod or to the cloth
* (net) charge on cloth is now negative
123
