paper reference(s) xxxx edexcel gcse...
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Paper Reference(s)
XXXX
Edexcel GCSE Physics Physics topic P3
Specimen structured paper
xxxday June 2007 – Morning/Afternoon
Time: 1 hour
Materials required for examination Items included with question papers
Pen None
Instructions to Candidates In the boxes above, write your Centre number and Candidate number, your surname, initial(s) and signature.
Use a pen. Do not open this booklet until you are told to do so.
Write your answers in this booklet.
All candidates are to answer all questions.
Show all the steps in any calculations and state the units.
You must not take this booklet out of the examination room.
Information for Candidates The total mark for this paper is 60. The marks for the various parts of questions are shown in round brackets,
eg: (2).
You may use a calculator.
Advice to Candidates
You are reminded of the importance of clear English and careful presentation in your answers.
Do any necessary calculations and rough work in this booklet.
Printer’s Log No.
W850/R1535/57570
This publication may only be reproduced in accordance with Edexcel copyright policy.
© 2006 Edexcel
Signature
Surname Initial(s)
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The following equations are provided for your use.
Pressure = constant Temperature
P = constant T
P1V1 P2V2
= T1 T2
Kinetic energy = electronic charge × accelerating voltage
KE = e × V
Work done = force × distance moved in the direction of the force
W = F × s
Power = work done/time taken P = W t
Frequency = 1/time period f = 1 T
Intensity = power of incident radiation Area
I = P A
Kinetic energy = ½ × mass × (velocity) 2 KE = ½ mv 2
Momentum = mass × velocity p = mv
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1.
John is trying to compare the properties of an electron, a positron and an alpha particle.Complete the grid that John has started.
mass in a.m.u charge fundamental particle
electron1
2000–1
positron yes
alpha 4 no
(4 marks)Total = 4 marks
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2. Janet has been suffering from severe stomach pains. Her doctor wants to use an endoscope to examine the lining of her stomach.
Janet looked up endoscopes on the web. She found an article which included this information:
Endoscopes are made of glass fibres. Each glass fibre in an endoscope has a transparent cladding round it.
These two pictures show what happens to light which is incident at two different angles on the end of the glass fibre.
80˚
15˚
cladding
cladding
glass fibre
diagram 2
23˚
75˚
cladding
cladding
glass fibre
diagram 1
P
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a) Suggest how the endoscope can be used by Janet’s doctor to examine her stomach.
_______________________________________________________________ (1 mark)
b) (i) In diagram 2, all of the light is reflected into the glass fibre at point P. What is the name of this effect?
_______________________________________________________________(1 mark)
(ii) Suggest a value for the critical angle at this boundary.
_______________________________________________________________(1mark)
c) Endoscopes usually have hundreds of thin fibres rather than just one thick fibre.Suggest a reason why thin fibres are used.
_______________________________________________________________
_______________________________________________________________ (1 mark)
Total = 4 marks
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3. (a) Shefali is a weight-lifter.
Her basal metabolic rate is 1500 calories/day.
(i) State one activity which contributes to her basal metabolic rate.
_________________________________________________________________ (1 mark)
(ii) During training, Shefali lifts 200 N ten times, in quick succession, through a height of 2.0 m. Calculate how much work she does in lifting 200 N once from the ground to a height of 2m.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________ (2 marks)
(iii) How many calories of energy (to 1 s.f.) is transferred when Shefali lifts the 200 N weights ten times to a height of 2 m?
You make take 1 calorie = 4 200 J.
________________________________________________________________
________________________________________________________________
________________________________________________________________(2 marks)
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(iv) A nurse uses a pulse oximeter to measure Shefali’s pulse and the percentage oxygen saturation in her blood.
Pulse oximeters use two LEDs. One LED emits red light and the other infra-red radiation.The emitted radiation which passes through some of the patient’s tissues is detected using an LDR.
Give two reasons why two types of LEDs are used.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________(2 marks)
(b) In a pulse oximeter, some light is absorbed by solid tissue and the blood. The amount of light absorbed is related to the percentage saturation of
oxygen in the blood. Some volunteers were given drugs to reduce the oxygen levels in their blood down to 70% saturation. While this was done the partial pressure of oxygen in the arteries was measured.
The results were used to produce a standardised graph as shown below.
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(i) Suggest a reason why 70% blood saturation was the lower limit for the volunteers.
__________________________________________________________________
__________________________________________________________________ (1 mark)
(ii) How reliable is the graph below 70% arterial oxygen saturation?
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________(2 marks)
Total = 10 marks
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4. (a) This is a graph of neutron number against proton number for stable isotopes.
(i) Put an A on the graph to show the position of an unstable isotope that would
decay by emission.(1 mark)
(ii) Put a B on the graph to show the position of an unstable isotope that would
decay by - emission.
(1 mark)
(b) At one time, scientists thought that protons and neutrons were fundamental particles.
In 1968 the discovery of quarks changed this idea.
Scientists now believe that protons and neutrons are made up of particles called quarks.
There are two types of quark, u and d. (i) What do the letters u and d stand for?
u = ________________________ d = ___________________________ (1 mark)
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(ii) Complete the table to show the numbers of quarks in a neutron and a proton.
particle total number of quarks
number of u quarks
number of d quarks
neutron 2
proton 3
(4 marks)
(iii) The charge on a neutron is zero. What does this suggest about the charge on a u quark compared with
the charge on a d quark?
__________________________________________________________________
__________________________________________________________________ (2 marks)
(iv) Neutrons can decay. This is used to explain -decay. Complete this equation for -decay.
neutron + ______________________
(1 mark)
(v) Explain what has happened to the quarks in a neutron when a neutron undergoes -decay.
__________________________________________________________________
__________________________________________________________________ (1 mark)
Total = 11 marks
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5. (a) Liam is a medical physicist.
He sometimes uses gamma radiation to treat some cancers like a brain tumour.
The diagram below shows a typical method.
collimated gamma source 2
collimated gamma source 3 collimated gamma source 1
brain tumour
(i) Why is gamma radiation used?
____________________________________________________________________
____________________________________________________________________ (1 mark)
(ii) Explain one reason why three (or more) beams of gamma radiation are used.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________ (2 marks)
(iii) Explain what happens to the brain tumour cells when they are hit by gamma radiation.
_________________________________________________________________
_________________________________________________________________ (1 mark)
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(b) Boron 10 is a stable isotope of boron which can readily absorb thermal neutrons.
(i) What is a thermal neutron?
____________________________________________________________________ (1 mark)
(ii) Complete the reaction to show this process by giving appropriate numbers for X and Y.
X __________ Y ___________ (2 marks)
(c) When boron absorbs the neutron, it becomes unstable and fissions into an alpha particle and a lithium nucleus.
Often gamma radiation is also emitted.
(i) Which of the fission products is likely to have the smallest range?
__________________________________________________________________ (1 mark)
(ii) Suggest a reason for your choice.
_________________________________________________________________ (1 mark)
(d) Liam uses Boron 10 in an experimental treatment for malignant brain tumour. Boron compounds are absorbed over 10 times more by cancer cells than by normal cells. They are non-toxic.
He injects compounds containing Boron 10 into his patient. Then he irradiates his patient’s head with a beam of thermal neutrons.
(i) Suggest how this process works to destroy cancer cells.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________ (2 marks)
ß X
Y
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(ii) Suggest two advantages that this method would have over treatment with gamma radiation (as in question 5(a)).
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________ (2 marks)
Total = 13 mark
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6. Sarah used the apparatus below to investigate what happens to the volume of a gas when the pressure is reduced while the temperature stays the same.
Sarah took readings of the volume as she added weights (loading) and as she removed the weights (unloading).
She recorded the results of her experiment in the table below.
(a) Suggest why she took two sets of readings for the volume.
___________________________________________________________________
___________________________________________________________________
(1)
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(b) Use the graph paper below to plot a graph of her average volume against pressure.
(4 marks) (c) Use the particle model to explain why the pressure of a gas increases when
the volume decreases.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________ (2 marks)
(d) Sarah was careful to keep the temperature constant during her experiment.
State and explain what would have happened to the pressure readings if she had allowed the temperature of the gas to increase.
________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________ (2 marks) Total = 9 marks
Vo
lum
e(m
l)
Pressure (kPa)
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7. Liam’s colleague, Rosita, works in a specialist unit for patients recovering from heart attacks.
(a) She uses a specialist type of oscilloscope to measure the electrical activity of her patient’s heart.
(i) In an oscilloscope electrons are emitted from a heated cathode. What is this process called?
_______________________________________________________________ (1 mark)
(ii) The electrons are then accelerated to an energy of 6.7 × 10-17J. Calculate the accelerating voltage. Give your answer correct to 3 significant figures and include the correct
unit. The charge on an electron is 1.6 × 10-19 C.
______________________________________________________________
______________________________________________________________
______________________________________________________________(3 marks)
(b) The oscilloscope trace shown below is an action potential from the sino- atrial node (sometimes called the pacemaker) of the heart.
What is the average frequency of this action potential? Show your working.
(2 marks)
y-a
xis
time (s)
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(c) The graph shown below is an ECG of a normal heart.
(i) On the trace, the P–wave is caused by the depolarisation and contraction of the atria.
Explain what causes the QRS–wave.
_______________________________________________________________
_______________________________________________________________ (2 marks)
(ii) Estimate the range of voltages detected at the surface of the patient.
_______________________________________________________________
_______________________________________________________________ (1 mark)
Total = 9 marks
TOTAL FOR PAPER = 60 MARKS
End of paper
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0.5
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