physics paper 1 Flashcards
(123 cards)
1
Q
A student recorded total resistance in a parallel circuit three times.
Reading 1: 15.8Ω
Reading 2: 15.3Ω
Reading 3: 16Ω
Mean: 15.7Ω
The student thought that taking a fourth reading would improve the precision of the results.
The fourth reading was 16.2Ω.
Explain why the student was wrong. (2)
A
- precise results show little variation
- the 4th result was further away from the mean that the other values
2
Q
Why would the time taken for a wire to melt increase if some energy was transferred to the surroundings?
A
more energy would need to be transferred
3
Q
Describe the current and potential difference in parallel circuits.
A
current is shared and p.d is the same
4
Q
A negatively charged student touches a metal tap and received an electric shock.
Explain why. (3)
A
- there is potential difference between the student and the tap
- which causes electrons to transfer from the student to the tap
- the tap is earthed
5
Q
The National Grid ensures that fossil fuel power stations in the UK only produce about 33% of the total electricity they could produce when operating at a maximum output.
Suggest two reasons why.
A
-so as to not make unnecessary environmental impact
- conserves fuel reserves
- spare capacity to compensate for unreliable renewable resources
- provides spare capacity in case of power station emergency shut-down
6
Q
The idea of obtaining power from nuclear fusion was investigated using models.
The models were tested before starting to build the first commercial nuclear fusion power station.
Suggest three reasons why models were tested.
A
- to make sure the fusion process is possible
- to develop an understanding of the process
- to make adaptations to the process
- to assess the efficiency of the process
- to make predictions
- assess safety risks
- to assess environmental impact
- set-up cost is lower (for small scale experiments)
7
Q
Nuclear power stations generate electricity through nuclear fission. Electricity can also box be generated by burning shale gas.
Shale gas is natural gas trapped in rocks. Shale gas can be extracted by a process called fracking. There is some evidence that fracking causes minor earthquakes. Burning shale gas adds carbon dioxide to the atmosphere.
Describe the advantages of nuclear power compared with the use of shale gas to generate electricity. (3)
A
- no carbon dioxide emitted
- doesn’t cause global warming
- nuclear power doesn’t cause earthquakes
- more energy released per kg of fuel
8
Q
A smoke alarm that detects smoke using alpha radiation would not work with a radiation source that emits beta or gamma radiation.
Explain why. (2)
A
- beta and gamma will penetrate smoke
- so no change (in count rate) will be detected
9
Q
A student becomes negatively charged because of the friction between his socks and the carpet.
Explain why the friction causes the student to become charged. (2)
A
- transfer of electrons
- from the carpet to the student
10
Q
Give 3 man-made sources of backround radiation.
A
- radioactive waste from nuclear power stations
- nuclear weapons (testing)
- x-rays
- radiotherapy
- named nuclear disaster e.g. Chernobyl / Fukushima / Three Mile Island.
11
Q
Suggest two precautions taken to reduce the hazard caused by radioactive waste from power stations.
A
- bury the radioactive waste
- cover the radioactive waste in concrete
- store the radioactive waste in metal containers
- put the radioactive waste in cooling ponds
- transport the radioactive waste in secure vessels
12
Q
Describe the resistance in parallel circuits.
A
total resistance of the circuit is lower than the resistance of the smallest individual resistor
13
Q
Suggest one reason why the baby bouncer should not be used with babies that have a mass greater than 12kg.
A
spring may become permanently extended
14
Q
In what order was the elctron, neutron, nucleus and proton discovered?
A
electron, nucleus, proton, neutron
15
Q
Explain how oiling the mechanical parts of a wind turbine would affect the efficiency. (3)
A
- the efficiency would increase
- because the percentage / proportion / amount of energy wasted would decrease
- (because) less (work is done against) friction
16
Q
It is dangerous for a person to fly a kite near an overhead power cable.
The person could receive a fatal electric shock if the kite was very close to, but not touching the power cable.
Explain why. (3)
A
- electric field strength is very high
- causing the air to become ionised or air becomes a conductor (of charge)
- (the kite) conducts charge to the person
17
Q
An electrician is replacing an old electric shower (connected to the mains electricity) with a new one.
If the electrician touches the live wire he will receive an electric shock.
Explain why. (4)
A
- potential of the live wire is 230V
- potential of the electrician is 0V
- large potential difference between the live wire and the electrician
- charge / current passes through his body
18
Q
Explain how the process of nuclear fuson leads to the release of energy. (2)
A
- lighter nuclei join to form heavier nuclei
- some of the mass is converted to energy
19
Q
What is meant by the ‘random nature of radioactive decay’?
A
can’t predict which nucleus will decay and when a nucleus will decay
20
Q
On one day the demand for electricity in the UK was 34000 MW.
Suggest two reasons why wind power was not able to meet this demand.
A
- wind is unreliable
- wind turbines don’t turn when the wind is too strong / weak
- there are not enough wind turbines
21
Q
A student left a thermometer in an iron block for a few minutes before recording the initial temperature.
Suggest why.
A
so the thermometer temperature was the same as the iron block
22
Q
Nuclear fission releases energy.
Describe the process of nuclear fission. (4)
A
- neutron absorbed by uranium nuclei
- nucleus splits into two parts / two - lighter daughter nuclei are formed
- energy and 2 or 3 neutrons are released
- and gamma rays are emitted
23
Q
Why do did some alpha particles get deflected at a greater angle than others? (2)
A
- they passed closer to the nucleus
- so they experienced a greater force
24
Q
Explain why different people have different speeds at the end of a zip wire. (2)
Give two different reasons and explain.
A
- different people have different surface areas
- so will be affected by air resistance differently
or - people may have different masses
- so their terminal velocity will be different
or - initial speed may not be zero
- which would add to the total energy of the system
25
Explain how an uncharged object my become positively charged. (3)
- negatively charged
- electrons are transferred
- from the (neutral) object
26
A negatively charged rod is placed on a balance and the reading on the balance is 74.85g
Another charged rod is held stationary above the rod on the balance; the rods do not touch each other.
Explain why the reading on the balance increases to 74.95g. (3)
- there is an additional (downwards) force on the balance (increasing the mass reading)
- (because) the (held) rod is negatively charged
- like charges repel
27
The maximum speed this cyclist can travel on a level road is 14 m/s.
How does cycling uphill affect the maximum speed of this cyclist?
Explain your answer. (3)
- maximum speed is lower
- because maximum power output of cyclist is constant
- (but) additional work is done (against gravity) **or** gravitation potential energy (of cyclist) is increased
28
Give one reason why a glass thermometer is more likely to be misread than an electric thermometer.
viewing angle affects measurements **or** parallax error
29
As a tyre is inflated, the internal energy of the air increased.
Explain why. (2)
- work is done on the air
- so temperature increases **or** kinetic energy of the particles increase
30
A student touches the metal dome of a static electricity generator.
Explain why the student's hair stands up on end. (3)
- electrons are transferred to the student
- (so) her hair is negatively charged
- (and) like charges repel
31
Flurorine-18 has a half life of 6584.34s.
A sample of fluorine-18 has an activity that is one quarter o its original activity.
Calculatae the age of the sample of fluorine-18. (2)
- two half-lives
- 13168.68s
32
Explain why the air pressure in a car tyre changes if the temperature of the air in the tyre increases. (4)
- (as temperature increases the) air particles have greater (mean) **kinetic energy**
- (so) more / increased frequenct of collisions with tyre (walls) per second
- (and) greater force in each collision
- greater (mean) force **per square metre** causes greater pressure (on wall of tyre)
33
A vending machine identified the resistance of coins by measuring the resistance of coins.
Coins that are dirty are not recognised by the vending machine.
Suggest one reason why.
dirt changes the resistance of the coin **or** the resistance is different from the expected resistance
34
What does the live wire do?
carries alternating p.d from the supply
35
There is a switch in a mains electricity lighting circuit in a house.
The electrician replaced the switch.
The electrician would have recieved an electric shock unless the circuit was disconnected from the mains supply.
Explain why. (3)
- wire in the switch is live
- electrician is earthed
- so there would’ve been a large potential difference between the electrician / earth and the (live) wire (if the electrician touched it / the live wire)
36
Explain the ideal properties of a radioactive source for use in medical diagnosis. (4)
**Indicative content**
- short half-life or half-life of a few hours
- (short half-life means) less damage to cells / tissues / organs / body
- low ionising power
- (low ionising power means) less damage to cells / tissues / organs / body
- highly penetrating
- (highly penetrating means) it can be detected outside the body
- emits gamma radiation
37
Engineers have developed a way of charging electric cars while they are driving along the road.
Coils of wire buring under the road transfer energy ot the car's battery as the car is passing over the coils.
Suggest two advantages of using this method to charge electric cars compared with plugging them into the mains electricity supply. (2)
- recharging is a continuous process
- more cars can be charged at the same time
- fewer cells needed in the car
38
What does 'direct potential difference' mean?
polarity does not change **or** potential difference in one direction
39
A 1 metre length of single aluminium wire is a better conductor than a 1 metre length of steel wire.
The individual wires behave as if they are resistors connected in parallel.
Explain why the current in the steel wire is different to the current in a single aluminium wire. (2)
- p.d across the wires is the same
- (but) the resistance of the steel wire is greater
40
The specific latent heat of fusion of ice is less than the specific latent heat of vaporisation of water.
Explain how a figure with temperature on the y-axis and time on the x-axis would show this. (2)
- it would take more time for water to vaporise than ice to melt
- so less energy is needed to change state from solid to liquid (than liquid to solid)
41
What is meant by a zero error?
when a measuring device displays a reading when not connected / should be zero
42
Describe the difference between irradiation and contamination. (2)
- irradiation is the **exposure** of an object/person to radiation
- contamination is the presence of radioactive material / atoms on an object / person
43
A student investigated how the current in the resistor **R** at a constant temperature varied with the potential difference across the resistor.
During the student's investigation the temperature of resistor **R** increased.
Explain how the increased temperature of resistor **R** would have affected the student's results. (2)
- resistance of **R** would increase
- current and potential difference would not be directly proportional
44
A student wanted to find the density of some fruits.
The student only measured the volume of each fruit once.
The volume measurements **cannot** be used to show that the method to measure volume gives precise readings.
Give the reason why. (1)
repeat readings need taking to show that the readings are close together
45
As a person moves down a zip wire, their increase in kinetic energy is less than their decrease in gravitational energy.
Explain why. (2)
- friction **or** air resistance
- causes thermal energy to be transferred to the surroundings
46
Some carpets have thin copper wires running through them. Students are less likely to receive electric shocks after walking on these types of carpet.
Suggest why. (2)
- carpet / copper has a low resistance **or** copper is a conductor
- lower / no build-up of charge (on the student) **or** (so there is a) smaller / no potential difference between student and earth
47
A solar power system is installed in the remote village in addition to the hydroelectric generator.
Explain why this improves the reliability of th electricity supply to the village. (2)
- druing the summer power output from the solar panels would be higher
- so there would be **less variation** in total power output
48
Explain how an electron can move up and down between energy levels in an atom. (2)
- to move to a higher energy level the electron absorbs energy from electromagnetic radiation
- to move to a lower energy level the electron emits energy in the form of electromagnetic radiation
49
A student measured the volume of a apple once.
The volume measurement **cannot** be used to show that an experiment involving the apple gave precise readings.
Give the reason why. (1)
A student measured the volume of a apple once.
The volume measurement **cannot** be used to show that an experiment involving the apple gave precise readings.
Give the reason why. (1)
50
Person A took a longer time to run up a set of stairs than Person B, but they had the same power output.
What conclusion can be made about the person A's mass?
A's mass was greater than B's
51
A student models the random nature of radioactive decay using 100 dice.
He rolls the dice and removes any that land with the number 6 facing upwards.
He rolls the remaining dice again.
The student repeats this process a number of times.
Give two reasons why this is a good model for the random nature of radioactive decay. (2)
you can not predict **which** dice / atom will ‘decay’
you can not predict **when** a dice / atom will ‘decay’
52
Give two reasons why it may be better to use a digital ammeter instead of a moving coil ammeter.
- less chance of misreading
- no parallax error **or** position of eyes does not affect reading
- higher resolution
1. - more accurate
53
Explain why **step-up** transformers are used in the National Grid. (4)
- increase potential difference
- and decrease current
- reducing thermal energy transfer to surroundings from transmission cables
- increasing the efficiency (of power transmission)
54
How does the resistance of a thermistor change as the temperature changes?
resistance of thermistor decreases as temperature increases
55
The half-lives of some radioactive isotopes are given below.
Nitrogen-18: 0.62s
Nitrogen-17: 4.17s
Fluorine-17: 64.37s
Fluorine-18: 6584.34s
All of the isotopes above emit beta radiation.
Explain which isotope would cause the biggest risk to a person's heallth based only on the half-life of each isotope. (3)
- Nitrogen-18
- greatest activity
- greatest dose of radiation absorbed (per second)
56
When electric cars are not being driven, energy stored in their batteries could be used to meet sudden peaks in electricity demand.
Suggest how.
- when cars are plugged in
- the energy from car batteries could be transferred back to the National Grid
57
In addition to power input, light bulbs should also be labelled with the rate at which they emit visible light.
Suggest why. (2)
- bulbs also transfer thermal energy
- the efficiency of the light bulb also needs to be considered
58
Explain why **step-down** transformers are used in the National Grid. (2)
- decreases potential difference
- to a safe(r) value
59
What does the neutral wire do?
completes the circuit
60
Draw the circuit symbol for an LDR.
[symbol sheet](https://docs.google.com/document/d/16AteFCFwBgCX_v8lPNJHRVBQJgAYU58S5pef-jcKkVU/edit?tab=t.0)
61
Describe the movement of particles of helium gas inside a balloon. (2)
- range of speeds
- moving in different directions **or** random motion
62
A student determined the specific latent heat of vaporisation of water.
The initial mass of the beaker and water was 0.080kg.
The final mass of the beaker and water was 0.071kg.
Some of the water evaporated before its temperature reached 100°C.
Explain how this affected the student's value for the specific latent heat of vaporisation. (2)
- the measured change in mass is too high **or** a smaller mass of water actually changed state at boiling point
- (so) student's value of specific latent heat is too low
63
The temperature of the helium in a balloon was increased.
The mass and volume of helium in the balloon remained constant.
Explain why the pressure exerted by the helium inside the balloon would increase. (4)
- particles have more kinetic energy
- so there will be an increased frequency of collisions with the walls of the balloon per unit time
- (also) greater forces will be exerted in collisions
greater force exerted on the **same area** (increasing the pressure)
64
Bananas are a source of backround radiation. Some people think that the unit of radiation dose should be changed from sieverts to Banana Equivalent Dose.
Suggest one reasons why the Banana Equivalent Dose may help the public be more aware of radiation risks. (1)
people are able to compare a radiation risk / dose / hazard to the radiation dose from (eating) bananas
65
The specific heat capactiy of ice is less than the specific heat capacity of water.
Explain how a figure with temperature on the y-axis and time on the x-axis would show this. (2)
- there would be a **steeper gradient** for ice than water
- which means less energy is needed to increase the temperature by a fixed amount
66
Explain the advantage of transmitting electricity at a very high potential difference. (3)
- (very high p.d means) very low current
- which means less (thermal) energy is transferred to surroundings
- which increases the efficiency of power transmission
67
A student determined the specific latent heat of vaporisation of water.
The initial mass of the beaker and water was 0.080kg.
The final mass of the beaker and water was 0.071kg.
Some thermal energy was transferred to the surroundings while the water was being heated.
Explain how this affected the student's value for the specific latent heat of vaporisation of water. (2)
- less energy was transferred to the water
- (so) student's value of specific latent heat was too high
68
pressure produces a force at **----- ------** to the wall of containers
right angles
69
Explain why adding resistors in parallel decreases the total resistance. (2)
- there are more pathways for charge to flow
- so the total current increases (when potential difference stays the same)
70
In a parallel circuit there are two pathways that current can follow.
In one pathway there is a variable resistor and an ammeter to measure the current.
There is an open switch in the other pathway.
Explain how closing the switch would affect the current in the variable resistor. (2)
- current would be (almost) zero
- the switch has (effectively) zero resistance
71
Explain why alpha particles are deflected when they are directed at a gold nucleus. (2)
- alpha particles and (gold) nucleus are both positively charged
- (and) like charges repel
72
The efficiency of solar cells in 0.15.
Explain why it is unlikely that **all** of the electricity that the UK needs can be generated by solar power systems. (2)
- a really large area of land would need to be covered with solar cells
- due to the low useful power output of the solar cells
73
At the bottom of a slide, all riders and their sleds have approximately the same speed.
Explain why. (4)
- ½ mv^2 = mgh **or** decrease in gravitational potential energy = increase in kinetic energy
- masses cancel on both sides of the equation **or** v^2 = 2gh
- speed only depends on vertical height
- variations will be due to air resistance / friction **or** different initial speed
74
Draw the circuit symbol for a battery.
[symbol sheet](https://docs.google.com/document/d/16AteFCFwBgCX_v8lPNJHRVBQJgAYU58S5pef-jcKkVU/edit?tab=t.0)
75
A negatively charged rod is held near an earthed conductor.
Explain why a spark jumps between the negatively charged rod and the earthed conductor. (3)
- the (large) potential difference between the two objects
- (causes negative) electrons to move (through the air)
- (from the rod) to the conductor
76
Explain how the paths of the alpha particles in the alpha particle scattering experiment were used to develop the nuclear model of the atom. (4)
- most alpha particles pass straight through the atom
- which shows that the atom is mostly empty space
- very few alpha particles are deflected through a large angle
- which shows the atom contains a nucleus where the mass / charge of the atom is concentrated
77
How does the resistance of an LDR change as the light intensity changes?
resistance of LDR decreases as light intensity increases
78
Explain why contamination of the inside of the human body by a radioactive material that emits alpha radiation is highly dangerous. (3)
- alpha radiation is highly ionising
- causing an increased risk of cancer **or** organ failure **or** mutation of genes / DNA **or** radiation sickness / poisoning **or** damage to cells / tissues / organs
- until the radioactive material is removed / excreted **or** activity of radioactive material reaches / approaches background radiation levels
79
A student investigates how the speed a motor lifts a weight changes as the mass of the weight differs.
Give the main way that the motor is likely to waste energy.
heating the surroundings
80
A polonium (Po) nucleus decays by emitting an alpha particle and forming a lead (Pb) nucleus.
Po → Pb + α
The lead (Pb) nucleus then decays by emitting a beta particle and forms a bismuth (Bi) nucleus.
Pb → Bi + β
The bismuth (Bi) nucleus then decays by emitting a beta particle and forms a polonium
(Po) nucleus.
Bi → Po + β
Explain how these three decays result in a nucleus of the original element, polonium. (3)
- one alpha decay would decrease proton number by 2
- two beta decays would increase proton number by 2
- so the proton / atomic number of the final nucleus is the same as the proton / atomic number of the original nucleus
81
A cloth and a plastic rod were rubbed together.
Explain why the cloth became positively charged. (3)
- electrons transferred from the cloth (to the rod)
- electrons are negatively charged
- (so) there are more positive charges than negative charges on the cloth
82
A torch uses an LED.
The cells that were put into the torch were the wrong way round.
Explain why the torch will not work. (2)
- charge will not flow through a diode in the reverse direction
- because it / the diode has a very high resistance (in the reverse direction)
83
Explain why people should be encouraged to use energy efficient devices. (2)
- more efficient devices need a lower energy / electricity input
- which would minimise the energy demand / environmental impact from electricity generation
84
What colour is the insulation covering the llive wire in a three-core cable?
brown
85
Suggest three safety precaution a teacher could have taken to reduce the radiation dose received.
- increase distance between source and teacher
- limit exposure time
- use tongs / forceps
- wear a lead apron
- staand behind safety screen
- point source away from teacher
- keep source in box unless in use
86
Give three environmental advantages of using a gas-fired power station to generate electricity compared with using a coal-fired power station.
- no sulfur dioxide released
- doesn’t cause acid rain
- no particulates released
- doesn’t cause global dimming
- less carbon dioxide released (per kg of fuel)
- less global warming
*allow climate change / greenhouse gases*
- no solid waste
- gas mining is less destructive than coal mining
87
When a plunger was pushed slowly into a syringe, the pressure in the syring increased.
The temperature of the air remained constant.
Explain why the pressure increased. (3)
- particles are close together
- increased frequency of collisions between air particles and syringe walls
- larger force on a smaller area / larger force per unit area
88
Explain why a spark jumps between a negatively charged rod and an earthed conductor. (3)
- (there is a large) potentital difference between the two objects
- (causing negative) electrons to move (through the air)
- (from the rod) to the conductor
89
A scientist could not distinguish whether Source K emitted beta radiation or gamma radiation.
Explain how an absorbing material could be used to show which type of radiation is emitted by Source K. (2)
- use an aluminium sheet
- beta radiation will not **penetrate** but gamma will
90
Workers in nuclear power stations are monitored to check the radiation they emit.
A worker stands 1 cm away from a radiation detector.
The amount of radiation the worker emits is recorded.
Explain why the worker needs to stand close to the radiation detector. (2)
- some radioactive materials emit alpha radiation
- (which) has a very short range in air
91
Ice changed from solid to a liquid and increasaed in temperature to 5 degrees celsius.
Explain the changes in the arrangement **and** movement of the particles as the ice melted and the temperature increased to 5 degrees celsius. (6)
**Level 3:** Relevant points (reasons / causes) are identified, given in detail and logically linked to form a clear account.
**Level 2:** Relevant points (reasons / causes) are identified, and
there are attempts at logical linking. The resulting account is not fully clear.
**Level 1:** Points are identified and stated simply, but their relevance is not clear and there is no attempt at logical linking.
**Indicative content**
* particles in a solid are in a regular pattern
* particles in a liquid are in a random arrangement
* particles in a solid are vibrating about fixed positions
* particles in a liquid are moving freely
* as the ice changes to water the temperature remains constant
* because as the ice changes to water the potential energy of the particles increases
* as the water warms the particles move faster
* so the kinetic energy of the particles increases
* internal energy is the total kinetic and potential energy of all the particles
*ignore any references to density of ice vs liquid water
ignore any references to spacing of particles*
92
A smoke alarm stays off while alpha particles reach the detector.
Why does the alarm switch on when smoke particles enter the casing? (1)
smoke absorbs / stops alpha radiation / particles
93
A girl runs up a flight of stairs.
Based on values for her gravitational potential energy and the time taken to run up the stairs, her power output is 735W.
The **total** power output of the girl was greater than 735W.
Suggest two reasons why.
- girl increases her kinetic energy as well as increasing her gravitational potential energy
- some energy transferred as thermal energy (to the surroundings)
94
A student measured the effect of different insulating materials on the temperature decrease of water.
Two materials caused the water to take 450s and 745s to decrease by 20°C respectively.
Explain how the results can be used to compare the thermal conductivity of the two materials. (2)
- (same) temperature decrease in a shorter time means a higher thermal conductivity
- (because) the rate of energy transfer is higher
95
Explain the advantage of radioactive waste having a shorter half-life. (2)
- activity decreases quickly / faster
- risk of harm decreases quickly / faster
96
The power output of a turbine is directly proportional to the kinetic energy of the air passing the blades each second.
Describe the effect on the power output when the wind speed is halved. (3)
- mass of air passing the turbine blades is halved which decreases kinetic energy by a factor of 2
- (wind speed is halved) decreasing kinetic energy by a factor of 4
- so kinetic energy decreases by a factor of 8
97
Which model was developed last?
1. Bohr
2. Nuclear
3. Plum pudding
4. Tiny sphere that cannot be divided
Bohr
98
A teacher wears polythene gloves as a safety precaution when handling radioactive materials.
The polythene gloves do not stop the teacher’s hands from being irradiated.
Explain why the teacher wears polythene gloves. (2)
to prevent contamination
which would cause damage / irradiation over a longer period of time
99
Explain what type of error would be caused if a student's eye was **not** in line with the level of a liquid in a measuring cylinder. (2)
- random error
- because the eye level would not be the same each time
100
Describe how an investigation could be improved to reduce the effect of random error. (2)
- repeat (the investigation)
- ignore anomalies **and** calculate a mean
101
What is the circuit symbol for thermistor?
[symbol sheet](https://docs.google.com/document/d/16AteFCFwBgCX_v8lPNJHRVBQJgAYU58S5pef-jcKkVU/edit?tab=t.0)
102
Desribe the pattern on the insulation covering the earth wire in a three-core cable.
green and yellow stripes
103
What does the earth wire do?
it's a safety wire to stop appliances from becoming live
104
Explain how the risk from internal contamination is different to the risk from external irradiation by a source of alpha radiation. (5)
- alpha radiation has a low penetrating ability
- alpha radiation is stopped by skin
- internally, alpha radiation is absorbed by living tissue / organs
- alpha radiation is highly ionising
- contamination will cause greater harm to cells / tissues / organs
105
What colour is the insulation covering the neutral wire in a three-core cable?
blue
106
How would you find negative values of current and potential difference in an investigation?
reverse the connection to the power supply
107
Which subatomic particle was discovered first?
electron
108
Explain how the process of nuclear fusion leads to the release of energy. (2)
- lighter nuclei join to form heavier nueclei
- some of the mass is converted to energy
109
What is an 'electric field'?
a region around a charged object where another charged object experiences a force
110
What is the National Grid?
a system of cables and transformers linking power stations to consumers
111
What unit is used to measure activity?
becquerels (Bq)
112
When the volume of gas inside a syringe increased, the pressure on the inside walls of the syringe decreased.
Explain why. (3)
- there is more time between collisions of particles and the walls of the syringe
**or**
there are less frequent collisions between the particles and the walls of the syringe
- (causing) a lower (average) force on the walls of the syringe
- (and) pressure is the total force per unit area
113
Describe the current and potential difference in **series** circuits.
current is the same and p.d is shared
114
A student observes a measuring cylinder when taking volume measurements.
Explain what type of error would be caused if the student's eye was **not** in line with the level of the liquid in the measuring cylinder. (2)
- random error
- eye position would be different every time
115
Explain why a smoke alarm would not work with a radiation source that emits beta or gamma radiation. (2)
- beta and gamma will penetrate smoke
- no change (in the count rate) would be detected
116
Suggest two safety precautions that a teacher could have taken to avoid becoming contaminated.
- wear gloves / apron
- handle source with tongs / forceps
- wear a lab coat
117
Draw the circuit symbol for an LED.
[symbol sheet](https://docs.google.com/document/d/16AteFCFwBgCX_v8lPNJHRVBQJgAYU58S5pef-jcKkVU/edit?tab=t.0)
118
A student conducts an experiment investigating the IV characteristics of a filament lamp.
The power output of the lamp is 1.0W when the potential difference across the lamp is 5.0V.
The student predicts that the pwer output would be 4.0W if the potential difference was doubled.
Explain why the student is **not** correct. (2)
- (for power output to quadruple) potential difference and current would both have to double
- (however) current doesn't double because resistance increases
119
A student used a cell that had a potential difference of 1.50 V.
Explain why the cell would not be an electrica hazard to the student. (2)
- potential difference is (very) low
- (so) no risk of electric shock **or** (so) no risk of electrocution
*allow less for no*
120
Explain what led to the plum pudding model of the atom being replaced by the nuclear model of the atom. (6)
**Level 3:** A detailed and coherent explanation is provided. The student gives examples that argue a strong case and demonstrate deep knowledge. The student makes logical links between clearly identified, relevant points.
**Level 2:** An attempt to link the description of the experiment and the results with differences between the two models. The student gives examples of where the plum pudding model does not explain observations. The logic used may not be clear.
**Level 1:** Simple statements are made that the nuclear model is a better model. The response may fail to make logical links between the points raised.
Indicative content
- alpha particle scattering experiment
- alpha particles directed at gold foil
- most alpha particles pass straight through
- (so) most of atom is empty space
- a few alpha particles deflected through large angles
- (so) mass is concentrated at centre of atom
- (and) nucleus is (positively) charged
- plum pudding model has mass spread throughout atom
- plum pudding model has charge spread throughout atom
121
Explain how the resistance of a filament lamp changes as the potential difference across it increases. (3)
- current increases
- temperature of filament increases
- resistance increases
122
Light intensity increases.
What happens to the potential difference across an LDR?
increases
123
Light intensity increases.
What happens to the current across an LDR?
decreases
