Download Phy Pre 08 - PembyPhysics

Student Number……………………………….
Preliminary Course
Yearly Examination 2008
Physics
General Instructions
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Reading time – 5 minutes
Working time – 2 hours
Board approved Calculators can be
used.
Write using blue or black ink
Draw diagrams using a pencil
Write your student number at the top
of each section
A data sheet and formula sheet are
provided on coloured paper.
Total marks 75
Part A-15 marks
Allow about 20 minutes for this section
Part B- 60 marks
Allow about 1 hour and 30 minutes for this
section
This paper must not be removed from the Examination Room
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Physics Preliminary 2008
Part A 15 marks
Use the multiple choice answer grid
Select the alternative A, B, C or D that best answers the question. Fill in the response oval
completely.
Sample 2 + 4 =
A
(A) 2
(B) 6
B
C
(C) 8
(D) 9
D
If you think you have made a mistake, put a cross through the incorrect answer and fill in the
next answer.
A
B
C
D
If you change your mind and have crossed out what you think you consider to be the correct
answer, then indicate this by writing the word correct and drawing an arrow as follows:
correct
A
B
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C
D
Physics Preliminary 2008
Section I
15 marks
Attempt Questions 1–15
Allow about 20minutes for this section
Use the multiple choice answer sheet for Questions 1 to 15.
1
Which of the following are all non-mechanical waves?
A
B
C
D
2
If the distance between a compression and an adjacent rarefaction of a sound wave is
0.6 m what is the wavelength of the sound wave?
A
B
C
D
3
B
C
D
The angle between the incident ray and the normal to the surface is always
equal to the critical angle
The angle between the incident ray and the normal to the surface is always less
than the critical angle
The angle between the incident ray and the normal to the surface is always
greater than critical angle
The angle of incidence is equal to the angle of refraction
What are the units of electric field?
A
B
C
D
5
0.6 m
0.12 m
2.4 m
1.2 m
Light rays can be sent down optical fibres with little loss because they are totally
internally reflected within the fibre. Why are the light rays totally internally reflected
within an optic fibre?
A
4
Water waves, sound waves, radio waves
Radio waves, X-rays, ultraviolet light, visible light
Visible light, ultraviolet light, X-rays, sound waves
Sound waves, microwaves, water waves
Newtons per coulomb
Coulombs per newton
Coulombs per joule
Joules per coulomb
What would happen to the electrical resistance of a length of nichrome metal wire if
the temperature of the wire was increased?
A
B
C
D
Increase
Decrease
Remain constant
Impossible to say
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Physics Preliminary 2008
6
How would the reading on the ammeter and voltmeter change if the globe marked X
in the circuit blew out?
A
B
C
D
7
What variable does a car speedometer measure?
A
B
C
D
8
16.7 kg and 163 N
163 kg and 163 N
100 kg and 163 N
16.7 kg and 980 N
What remains constant when two cars collide?
A
B
C
D
11
Driving around a bend at constant speed
Slowing down at a stop sign
Starting from rest
Driving up a hill at constant velocity
On the surface of the moon the acceleration due to gravity is one sixth that on the
Earth. If an astronaut had a mass of 100 kg on Earth, what would his mass and weight
be on the moon?
A
B
C
D
10
Instantaneous velocity
Average velocity
Average speed
Instantaneous speed
Which of the following motions of a car do NOT involve acceleration?
A
B
C
D
9
Both the current and the voltage would decrease.
Both the current and voltage would increase.
The current would decrease and the voltage would not change.
The voltage would increase and the current would not change.
The sum of the kinetic energy of the cars only
The vector sum of the momentum on the cars
Both the sum of the kinetic energy and the sum of the momentum of the cars
The momentum of each car
What is the main source of power in a red giant star?
A
B
C
D
Fusion of hydrogen nuclei
Fission of nuclei heavier than hydrogen
Fusion of helium nuclei
Fission of nuclei heavier then helium
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Physics Preliminary 2008
12
What can be deduced about the galaxy from the shift in the spectral lines emitted from
the galaxy shown in the diagram?
Spectra from excited hydrogen gas on Earth
200
400
Wavelength ( 10–9 m)
600
Spectra of hydrogen from a distant galaxy
200
A
B
C
D
13
400
Wavelength ( 10–9 m)
600
The galaxy is moving towards the Earth.
The galaxy is moving away from the Earth.
The galaxy has a super massive black hole at its centre.
The galaxy is in the process of colliding with another galaxy.
What factor(s) determine the brightness of a star when it is viewed from the Earth?
A
B
C
D
14
The distance to the star alone
The luminosity of the star and the distance to the star
The colour and size of the star
The surface temperature and size of the star
Which of the following types of radiation would cause the most ionisation when it
passed through air?
A
B
C
D
15
Beta
Microwave
Gamma
Alpha
In the diagram below all the resistors shown are identical.
If the ammeter reads 1.0 A, the current delivered from the battery must be:
A
B
C
D
1.0 A
2.0 A
2.5 A
3.0 A
End of Section I
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Physics Preliminary 2008
Section II
55 marks
Attempt Questions 16–26
Allow about 90 minutes for this section
Answer the questions in the spaces provided.
Show all relevant working in questions involving calculations.
Marks
Question 16 (6 marks)
A water wave is shown in the diagram above.
(a)
What is the amplitude of the wave?
1
(b)
Given that the wave has a velocity of 1.2 ms–1, determine the frequency of this
water wave.
2
Outline the key differences between light waves and sound waves.
3
(c)
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Physics Preliminary 2008
Marks
Question 17 (4 marks)
When space engineers design communication satellites they must ensure that the
microwave transmitters have sufficient power for signals to reach the Earth with
enough intensity to be detected.
(a)
(b)
Microwaves pass readily through the atmosphere. Name TWO other types of
electromagnetic radiation that do not pass readily through the atmosphere.
2
Microwaves from a communication satellite 400 km above the surface of the
Earth reach the surface with an intensity of 45 Wm–2. Calculate the intensity of
the microwaves that would reach the surface if the satellite was moved to a new
orbit 1200 km above the surface.
2
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Physics Preliminary 2008
Marks
Question 18 (4 marks)
The diagram below shows a positively charged Perspex rod and negatively charged
electroscope when they are far apart.
The positively charged rod is gradually brought closer to the negatively charged electroscope.
As this motion takes place the leaves of the electroscope are observed to first collapse and
then diverge.
Explain what is happening by drawing three labelled sketches of the rod and electroscope
showing the charge distributions when the leaves are:
(a) in the process of collapsing
(b) fully collapsed
(c) beginning to diverge again.
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Physics Preliminary 2008
Marks
Question 19 (5 marks)
The diagram above shows how a light ray is refracted when it moves from air to Perspex
(transparent plastic). Note that the angle of incidence is 40 and that Perspex has a refractive
index of 1.20.
(a)
(b)
Compare qualitatively the velocity, frequency and wavelength of the light wave
in the air to the velocity, frequency and wavelength of the light wave in the
Perspex (no calculations required).
3
Calculate the angle of refraction of the ray when it enters the block of Perspex.
2
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Physics Preliminary 2008
Marks
Question 20 (6 marks)
The graph shown above illustrates the results found from an experiment that measured the
current passing through a resistor when various voltages were applied across the resistor.
The resistor was placed in a water bath to ensure that the temperature of the resistor did not
change throughout the experiment.
(a)
Draw a circuit diagram to show how the components below would have been
connected by the student to conduct this experiment. Label the direction of
current flow in your diagram.
3
(b)
Find the gradient of the graph and its units.
2
(c)
On the graph shown above, sketch the shape of the line (general trend only
required) that would have been obtained by the student if a water bath had NOT
been used in the experiment.
1
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Physics Preliminary 2008
Marks
Question 21 (3 marks)
The diagram above shows two charged parallel plates.
(a)
(b)
Sketch the electric lines of force between the two charged plates in the
diagram above.
1
If the electric field strength between the plates was 200 NC–1, determine the
mass of an oil droplet with a charge of –2.0  10–6 C which can be suspended at
rest between the plates.
2
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Physics Preliminary 2008
Marks
Question 22 (6 marks)
The 1800 kg car shown in the diagram above accelerates uniformly from rest to a speed of
72 km hr–1 in a time interval of 5 seconds.
(a)
Calculate the final kinetic energy of the car.
2
(b)
Determine the work done on the car during the time when it was accelerating.
1
(c)
Calculate the acceleration of the car.
2
(d)
Determine the distance travelled by the car in the 5 second time period.
1
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Physics Preliminary 2008
Marks
Question 23 (3 marks)
A current carrying solenoid and a magnet are fixed to trolleys as shown below. The mass of
the solenoid and trolley is four times the mass of the magnet and trolley. The two trolleys are
placed a distance d apart and released.
Assuming momentum is conserved and that the two trolleys are released from rest.
(a) Determine the direction of motion of these two trolleys.
1
(b) Calculate the ratio of the acceleration of the magnet trolley to the acceleration of the
solenoid trolley.
2
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Physics Preliminary 2008
Marks
Question 24 (5 marks)
The Sun is a G2 Main sequence star with a surface temperature of 6000°C. The Sun radiates
electromagnetic radiation and particles into space and undergoes a sunspot cycle with a period
of approximately 11 years.
(a)
State the energy source of a main sequence star.
1
(b)
Outline the nature of sunspots and the reason that scientists on earth are studying
them closely.
2
(c) Explain two pieces of evidence for the Big Bang theory.
2
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Physics Preliminary 2008
Marks
Question 25 (5 marks)
Describe TWO principal models of the solar system that were developed by scientists
from the time of Aristotle to the time of Newton, and evaluate the importance of
technology to the development of these models.
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Physics Preliminary 2008
Question 26 (5 marks)
The equipment below was used to find the relationship between the net force and acceleration
of the trolley. A data logger attached to a light gate was used to find the acceleration. the
spring balance was used to find the net force.
End of paper
The hanging mass M was changed to collect a range of data shown below.
Net Force (N)
Acceleration (ms-2)
1.0
0.9
2.0
1.6
3.0
2.3
4.0
2.9
5.0
3.7
6.0
4.4
(a) State the physical principle being tested in this experiment?
1
(b) Plot the net force versus acceleration on the grid below. Include a line of best fit.
2
(c) Use the graph to find the mass of the trolley.
2
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Physics Preliminary 2008
Question 27. (5 marks)
Identical resistors, each of value R ohm, are arranged in 3 circuits I, II, III as shown in the
diagram below.
The voltage applied to each circuit was varied and potential difference versus current graphs
were plotted for each circuit, as shown below.
(a) Which graph, X, Y or Z relates to which circuit? (Justify your answer)
2
(b) Calculate the value of R
2
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Physics Preliminary 2008
potential difference (V)
(c) The switch in circuit III is closed and the applied voltage again varied. Plot a potential
difference versus current graph for this circuit under these conditions on the graph below.
12
9
6
3
2
4
6
8
current (A)
1
Question 28 (3 marks) Assess one negative impact on society since the discovery and use of
electricity in households.
3
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Physics Preliminary 2008
Section I – Multiple choice
Answer sheet
A
B
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
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C
D
Physics Preliminary 2008
Mapping grid
Question Mark
Content
Outcome
Band
P8
2–3
1
1
8.2.1 Col 2 dot 3
2
1
8.2.1 Col 2 dot 4 and 8.2.2 Col 2 dot 2
P8, P14
4–5
3
1
P5, P8
4–5
4
1
8.2.4 Col 2 dot 7 and 8
8.2.2 Col 3 dot 1
P8
3–4
5
1
8.3.2 Col 2 dot 3
P13
4–5
6
1
8.3.3 Col 2 dot 2
P9
5–6
7
1
8.3.4 Col 2 dot 3 and Col 3 dot 2
P7
4–5
8
1
8.3.2 Col 2 dot 10
P7
2–3
9
1
8.4.1 Col 2 dot 4
P6
2–3
10
1
8.4.2 Col 2 dot 6 and 8
P13
4–5
11
1
8.4.2 Col 2 dot 7
P6, P9
4–5
12
1
8.4.4 Col 2 dot 3
P6, P7
5–6
13
1
8.5.3 Col 2 dot 4
H7
3–4
14
1
8.5.2 Col 2 dot 1
P14
5–6
15
1
8.5.3 Col 3 dot 1
P14
4–5
16
1
8.5.4 Col 2 dot 2
P7
4–5
17
6
8.2.1 Col 2 dot 2, 4, 5 and 6 and Col 3 dot 6
P8, P14
3–5
18
4
8.2.3 Col 2 dot 2 and dot 4
P8, P14, P7
4–6
19
6
8.2.4 Col 2 dot 4,5 and 6 and Col 3 dot 3 and 4
P8
3–5
20
6
8.3.2 Col 2 dot 9 and 10 and Col 3 dot 3 and 4
8.3.3 Col 2 dot 3 and 4
P11, P14
3–5
21
3
8.3.2 Col 2 dot 1 and Col 3 dot 1and 2
P6, P9
2–4
22
6
8.3.5 Col 2 dot 4 and Col 3 dot 1
P9, P11, P13
3–6
23
6
8.4.2 Col 2 dot 6 8.4.3 Col 2 dot 1 and Col 3
dot 1 and dot 3
P6, P7, P12
3–5
24
7
8.4.4 Col 2 dot 1 and Col 3 dot 3
P6, P7
2–6
25
5
8.5.4 Col 2 dot 3,4 and 6 and Col 3 dot 2
and 8.5.3 Col 2 dot 1 and 2 and Col 3 dot 1
P7, P10
3–5
26
5
8.5.1 Col 2 dot 1 and 8.5.3 Col 2 dot 1 and 2
P1, P2, P3
3–6
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Physics Preliminary 2008
This page has been intentionally left blank
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Physics Preliminary 2008
Marking guidelines
Section I
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
B
D
C
A
A
C
D
D
C
D
B
A
B
D
C
Distance between adjacent compression and rarefaction is half wavelength.
Section II
Question 16(a)
Criteria
 Correct numerical answer
Marks
1
Suggested answer:
Amplitude is the maximum displacement from the equilibrium position = 50 cm.
Question 16(b)
Criteria
 Correct numerical answer and units given
 Wave equation given, but incorrect answer OR correct numerical answer
with the wrong units given
Suggested answer:
v 1.2
f  
= 0.6 Hz
 2
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Marks
2
1
Physics Preliminary 2008
Question 16(c)
Criteria
Marks
 THREE or more differences clearly described
3
 TWO differences clearly described
2
 ONE difference given
1
Suggested answers:
LIGHT
speed of travel at 3x108m/s in air
are non mechanical waves
are em waves and can travel through vacuum
Are transverse waves
SOUND
slower (about 3330m/s) in air
mechanical waves
are mechanical waves and cannot travel
through a vacuum
are longitudional waves
Question 17(a)
Criteria
Marks
 TWO correct regions of the electromagnetic spectrum stated
2
 ONE correct regions of the electromagnetic spectrum stated
1
Suggested answers:
X-rays, ultraviolet light (or gamma rays)
Question 17(b)
Criteria

Marks
2
Correct numerical answer
1
stated but incorrect answer
1
r2
Suggested answer:
1
Intensity is proportional to 2 and hence as the distance is increased by a factor of 3 the
r
1 1
45
intensity will decrease by a factor of 2  and intensity will decrease to
= 5 Wm–2.
3
9
9

OR
I1r21=I2r22
45*4002=x*12002 so I=5Wm-2
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Physics Preliminary 2008
Question 18 (a)
All steps understood and explained. No extreme statements like “all
the electrons have left the leaves”
2 steps well understood and explained
1step well understood and explained
Some understanding of why the leaves move
4
3
2
1
(a) Electrons which are free to move go up because they are attracted to the Perspex rod. The
leaves which were very negatively charged are less charged and so move together. (leaves are
still slightly nebative
(b) As Perspex rod moves closer even more electrons are at the top and the overall charge at
the leaves has now become neutral.
(c) At the Perspex moves closer again so many electrons have left the leaves that they become
positively charged and repel each other because they both are positively charged
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Physics Preliminary 2008
Question 19(a)
Criteria
Marks
 All THREE comparisons correct
3
 TWO correct comparisons
2
 ONE comparison correct
1
Suggested answer:
When the light enters the Perspex:
 velocity decreases
 wavelength decreases
 frequency remains unchanged.
Question 19(b)
Criteria
Marks
 Correct answer
2
 States Snell’s law but does not obtain correct answer
1
Suggested answer:
sin i v1 c
  n
sin r v2 v2
 sin 40 
Hence r  sin 1 
  32.39° (or 32°23)
 n 
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Physics Preliminary 2008
Question 20(a)
Criteria
Marks
 Correct diagram
3
 ONE error in diagram (e.g. current flow direction, voltmeter not in parallel,
ammeter not in series, a short circuit)
2
 TWO errors in diagram
1
Suggested answer:
Question 20(b)
Criteria
Marks
 Correct answer and units
2
 Correct numerical but incorrect units
1
Suggested answer:
rise
Gradient =
= 15 VA–1 or 15 ohms
run
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Physics Preliminary 2008
Question 20(c)
Criteria
Marks
 Increasing gradient shown on graph
1
Suggested answer:
Question 21(a)
Criteria
Marks
 Correct diagram of field lines
1
Suggested answer:
Question 21(b)
Criteria
Marks
 Correct magnitude and direction
2
 Correct magnitude of 1 force only
1
Suggested answer:
F = qE = mg so (–2  10–6)  200 = m  9.8
so m=4.08x10-5kg
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Physics Preliminary 2008
Question 22(a)
Criteria
Marks
 Correct conversion to ms–1 and correct answer for kinetic energy
2
 Correct use of KE equation, but incorrect answer (e.g. due to error in
converting km hr–1 to ms–1)
OR
 Correct conversion to ms–1 but incorrect answer for the kinetic energy
Suggested answer:
1000
72 km hr–1 = 72 
= 20 ms–1
3600
1
1
Kinetic energy = mv2 = (1800)(20)2 = 360 000 joules
2
2
1
Question 22(b)
Criteria
Marks
 Correct answer OR the same answer that the student gave for part (a)
1
Suggested answer:
The work done is equal to the gain in kinetic energy and hence work = 360 000 joules.
Question 22(c)
Criteria
Marks
 Correct numerical answer
OR
 Correct working, but incorrect answer due to failure to convert
km hr–1 to ms–1
Suggested answer:
(v  u ) (20  0)

v = at + u and hence a =
= 4 ms–2
t
5
Question 22d
Criteria
 Correct numerical answer
1
Marks
1
r=ut+ ½ at2=50m
Question 23(a)
Criteria
 Correct direction
Marks
1
Towards each other
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Physics Preliminary 2008
Question 23(b)
Criteria
Marks
 Correct answer with logical working
2
 Attempt to use F=ma or similar and varying mass
1
4:1
Question 24(a)
Criteria
Marks
 Hydrogen fusion (fusion alone is not enough)
1
Suggested answer:
The fusion of hydrogen to helium in the core of the star converts mass into energy (in
accordance with Einstein’s equation E = mc2).
Question 25(b)
Criteria
Marks
 Answer which explains that sunspots are regions on the Sun’s surface that
are at a lower temperature AND that the cooling is caused by intense
magnetic fields and affect power systems
2
 Correctly states ONE of the two points above
1
Suggested answer:
Sun spots are regions on the Sun’s surface that are at a lower temperature than the rest of the
surface and hence appear to be darker than the surface around them. Sunspots are believed to
be caused by intense magnetic fields cooling regions on the outer layer of the Sun. they
produce massive amounts of particles that can rush to the earth and affect satellites and power
systems.
Question 24c
Criteria
Marks
 Two pieces of evidence well explained
2
 Correctly states ONE of the two points above
1
(Doppler red shift, Helium shortage, Hubble image)
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Physics Preliminary 2008
Question 26
Criteria
Marks
 A clear description of both models (ideally with diagrams) and an
evaluation statement about the importance of technology supported by
examples of technologies that enabled the models to evolve
5
 A good description of the two models and some discussion of technologies,
but no evaluation statement about the importance of technology
OR
 A good description of the models with a weakly supported evaluation
statement about the importance of technology
4
 An answer which includes a reasonable description of the models but fails
to link the development of the models with developments in technology
OR
 Answers that only describe the models or the technologies that influenced them
2–3
 A correct description of ONE model or ONE relevant technology
1
Suggested answer:
Around 300 BCE, Aristotle proposed an Earth-centred (Geocentric model) in which the Sun,
Moon and planets moved on crystal spheres around a stationary central Earth. The stars were
on the outermost sphere. This model was further developed by Ptolemy and accepted for over
1500 years. In the 16th century, accurate measurements by Brahe using new instruments
(large quadrants) cast doubts on some of the predictions of the Geocentric model. Copernicus
tried to explain these problems by using a sun-centred (Heliocentric) model of the solar
system in which the Earth and other planets revolved around a central stationary sun. These
models were in competition with one another until Galileo used the newly-discovered
telescope to make a number of observations that supported the Heliocentric model and
eventually led to the Heliocentric model replacing the Geocentric model. The development of
technologies (such as quadrants and telescopes) has been extremely important to the
development of our understanding of the solar system.*
*Note that diagrams could also be used by students to reduce the writing required in this answer.
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Physics Preliminary 2008
Question 26
(a) Newtons 2nd law
(b) Plot the net force versus acceleration on the grid below. Include a line of best fit.

6

5

3

2
1
Slope =rise/run
=4.2/3
=1.4kg
4.2N

4

3m/s/s
1
2
3
4
5
6
2
(c)
Criteria
Marks
 Slope correctly calculated
2
 Slope attempted
1
Resistance is the slope =1.4kg
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Physics Preliminary 2008
Question 27. (5 marks)
Criteria
Marks
 All correct with good justification
2
 One correctly matched with justification
1
X=I, Y=III, Z=II
Circuit 3 has the least resistance (R/2) and so has the shallowest slope.
Circuit II has the greatest resistance (2R) and so has the steepest slope
(b) R= slope of graph X=3Ω
(c) Total resistance =(1/R+1/R+1/R)-1=R/3 as R=3 Ω then the slope needs to be 1
Criteria
Marks
2
 Correct slope from wrong calculations OR Correct calculation but wrong
slope
1
potential difference (V)
 All correct with good justification
12
9
6
3
2
4
6
8
current (A)
1
Question 28
Criteria
Marks
 Assesses the impact
3
 Explains the impact
2
 Names an impact
1
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