Download P3 B to Aplus - crypt

Q1.
The diagram below shows an outline of a balance. The balance is used to weigh lorries. A
fraction of the weight of a lorry is used as the load on the right side of the pivot.
A standard weight W is moved along the arm until the weight of the load is balanced.
(a)
As the weight W is moved away from the pivot it can support a heavier load.
Why is this?
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(2)
(b)
(i)
The weight W is 100 N. When it is 0.2 m from the pivot it balances the load.
Calculate the moment of the weight W about the pivot.
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Answer ..................................... Nm
(2)
(ii)
The load is one hundredth of the weight of the lorry and is 0.02 m from the pivot.
Calculate the weight of the lorry.
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Answer ..................................... N
(2)
(Total 6 marks)
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Q2.
The diagram below shows a door lock which can be opened from a flat inside a building.
(a)
Explain how the door is unlocked when the switch is closed.
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(4)
(b)
State two changes which would increase the strength of the electromagnet.
1 ..................................................................................................................................
2 ..................................................................................................................................
(2)
(c)
Why is the spring needed in the lock?
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(1)
(d)
The connections to the coil were accidentally reversed. Would the lock still work?
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Explain your answer.
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(2)
(Total 9 marks)
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Q3.
The diagram shows apparatus used to demonstrate the motor effect. X is a short length of
bare copper wire resting on two other wires.
(a)
(i)
Describe what happens to wire X when the current is switched on.
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(ii)
What difference do you notice if the following changes are made?
A
The magnetic field is reversed.
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B
The current is increased.
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(3)
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(b)
The diagram shows a coil placed between the poles of a magnet. The arrows on the sides
of the coil itself show the direction of the conventional current.
The arrows labelled F show the direction of the forces acting on the sides of the coil.
Describe the motion of the coil until it comes to rest.
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(3)
(c)
Most electric motors use electromagnets instead of permanent magnets. State three of
the features of an electromagnet which control the strength of the magnetic field obtained.
1 ................................................................................................................................
2 ................................................................................................................................
3 ................................................................................................................................
(3)
(Total 9 marks)
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Q4.
(a) The diagrams show a windsurfer pulling up the sail of a sailboard. The mast pivots at
point P.
In which position, A, B or C must the windsurfer pull with the largest force? Give a reason
for your answer.
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(2)
(b)
Once the mast is upright, the windsurfer and the sailboard are in equilibrium.
(i)
What does in equilibrium mean?
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(1)
(ii)
The weight of the windsurfer is 700 newtons. Use the equation below to calculate the
moment exerted by the windsurfer on the sailboard. Show clearly how you work out
your answer.
moment = force × perpendicular distance from pivot
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Moment = ......................................... Nm
(2)
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(iii)
Use the relationship below to calculate the horizontal force of the wind on the sail.
Show clearly how you work out your answer.
total clockwise moment = total anticlockwise moment
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Force = ........................................ N
(2)
(c)
As the wind speed increases the windsurfer leans further out from the sailboard.
This position allows the windsurfer and sailboard to stay in equilibrium. Explain why.
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(3)
(Total 10 marks)
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Q5.
(a)
(i)
The diagram shows a lifebelt. It is hanging freely from hook Y.
On the diagram, mark with an X the point where you think the centre of mass of the
lifebelt will be.
(1)
(ii)
Explain why you have chosen this point.
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(2)
(b)
The drawing shows Susan on a diving board. She is 1.5 metres from point P and she
weighs 500 N.
Calculate her moment (turning effect) about point P.
Show clearly how you work out your answer and give the unit.
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Moment about P = ................................................
(3)
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(c)
Susan has a case with wheels.
When she packs this case, she puts the heaviest items at the end where the wheels are.
This means that the heaviest items are less likely to crush the other contents and it helps
her to find things when she opens the case.
Explain another advantage of packing her case in this way.
To gain full marks in this question you should write your ideas in good English. Put them
into a sensible order and use the correct scientific words.
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(4)
(Total 10 marks)
Q6.
After a person is injured a doctor will sometimes ask for a photograph to be taken of the
patient’s bone structure, e.g. in the case of a suspected broken arm.
(i)
Which type of electromagnetic radiation would be used to take the photograph?
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(1)
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(ii)
Describe the properties of this radiation which enable it to be used to photograph bone
structure.
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(2)
(Total 3 marks)
Q7.
(a) A student investigated the refraction of light as it passes out of a transparent plastic
block.
She aimed a ray of light at point X. She marked the position of the ray as it passed through
the transparent plastic block and into the air.
The angle i is the angle of incidence.
(i)
What is the name of angle r?
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(1)
(ii)
What is the name of the dashed line?
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(1)
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(b)
A camera uses a lens to produce an image which falls on a light detector.
Name a light detecting device which may be used in a camera.
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(1)
(c)
The diagram shows the position of an image formed in a camera.
(i)
What type of lens is shown in the diagram?
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(1)
(ii)
Use the equation in the box to calculate the magnification.
magnification =
Show clearly how you work out your answer.
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Magnification = ....................
(2)
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(d)
Why does the image formed in a camera have to be a real image?
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(1)
(Total 7 marks)
Q8.
The diagram shows the cross-section of an eye.
(a)
Use words from the box to complete each sentence.
ciliary muscle
cornea
iris
pupil
The shape of the lens is changed by the ....................................................... ,
this allows the lens together with the ......................................... to focus light
onto the retina.
(2)
(b)
A man, as he gets older, needs to hold a book further from his eyes in order to be able to
see the writing clearly.
The diagram shows that his eye lens is not able to focus light on the retina.
(i)
How has the ‘near point’ of the man’s eyes changed as he has got older?
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(1)
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(ii)
The problem can be solved by wearing reading glasses.
Complete the diagram below to show how the lens below is able to correct the
man’s vision.
(2)
(c)
Give two similarities between an eye and a camera.
1 .....................................................................................................................
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2 .....................................................................................................................
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(2)
(Total 7 marks)
Q9.
Ultrasound can be used in industry for detecting internal cracks in metals.
(a)
State two features of ultrasound.
1 ..................................................................................................................................
2 ..................................................................................................................................
(2)
(b)
The diagram shows an ultrasound transmitter and detector fixed to the front of a metal
block. The block has an internal crack.
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The diagram below shows the screen of the oscilloscope connected to the detector.
(i)
Explain why pulse A and pulse B occur.
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(2)
(ii)
The metal block is 120 mm from front to back. What is the distance, in mm, from the
front of the block to the internal crack?
Distance = .................... mm
(1)
(Total 5 marks)
Q10.
Pigs have a layer of fat in their skin. Underneath the fat is a layer of muscle. Ultrasonic
waves are used to measure the thickness of the layer of fat. An ultrasound transmitter and
detector are attached to the skin of the pig.
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(a)
Explain why ultrasound can be used to measure the thickness of the layer of fat.
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(2)
(b)
The oscilloscope does not measure distance directly.
(i)
What does the oscilloscope measure in this case?
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(1)
(ii)
What other information is needed to calculate the thickness of the layer of fat in a
pig?
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(1)
(Total 4 marks)
Q11.
The diagram shows a ray of light passing through a diverging lens.
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(a)
Use the information in the diagram to calculate the refractive index of the plastic used to
make the lens.
Write down the equation you use, and then show clearly how you work out your answer.
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Refractive index = ..................................
(2)
(b)
The focal length of the lens is 5 cm. A student looking through the lens sees
the image of a pin.
Complete the ray diagram below to show how the image of the pin is formed.
(3)
(Total 5 marks)
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Q12.
The diagram shows the image IC formed by a lens, of an object OB a long way from it. The
points F mark the focal points of the lens.
(a)
Describe, either by writing below or drawing on the diagram, how the size and position of
the image changes:
(i)
when the object OB is moved towards the focal point F.
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(ii)
when the object OB is moved past F to a point nearer the lens than the focal point.
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(4)
(b)
Explain how a converging lens in a camera is used to produce sharp images on the film
when the object is a long distance away from the camera, and when it is close to
the camera.
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(3)
(Total 7 marks)
Q13.
A transformer is used to reduce the 230 V a.c. mains to the 12 V supply required for the
lighting system. The transformer has 1150 turns on its primary coil.
(i)
Write down the equation which links the number of turns of each transformer coil to the
voltage across each transformer coil.
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(1)
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(ii)
Calculate the number of turns on the secondary coil of the transformer. Show clearly how
you work out your answer.
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number of turns on the secondary coil = .........................
(2)
(Total 3 marks)
Q14.
(a) An appliance in a house has a transformer. The transformer is used to reduce the
voltage to the level needed by the appliance.
The diagram shows the transformer.
(i)
Name the material used for the core of the transformer.
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(1)
(ii)
The transformer has 10 000 turns on the input side and 2000 turns on the output
side. If the mains voltage of 240 volts is applied to the input, calculate the output
voltage. You may find the following information helpful:
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(3)
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(b)
Explain, in terms of magnetic fields, how a transformer works.
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(4)
(c)
A 12 V car battery is connected to the input leads of the transformer. It is hoped to reduce
the voltage to 2.4 V in order to run a small motor. When the output voltage is measured it
is found to be zero.
Explain why the output voltage is zero.
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(2)
(Total 10 marks)
Q15.
The diagram shows the basic structure of a transformer.
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(a)
Explain how a transformer works.
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(5)
(b)
A transformer is used to change the 230 volt mains electricity supply to the 12 volts
needed to operate a low voltage halogen lamp. The current through the halogen lamp is
4 amps.
Calculate the current drawn by the transformer from the mains electricity supply.
Assume that the transformer is 100 % efficient.
Write down the equation you use, and then show clearly how you work out your answer.
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Current = ........................................... amps
(2)
(Total 7 marks)
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M1.
(a)
moment/torque increases as moves away
gains 2 marks
leverage/force increases as moves away
gains 1 mark
2
(b)
(i)
20
gains 2 marks
else working
gains 1 mark
2
(ii)
100 000 ecf
gains 2 marks
else working
gains 1 mark
2
[6]
M2.
(a) current flows
coil / core magnetised / electromagnet activated / energised / turned on
attracts iron bar causing bolt to be pulled out
each for 1 mark
4
(b)
more turns
bigger current / e.m.f
softer iron core
any two for 1 mark each
2
(c)
to relock door / return iron bar / to lock door
for 1 mark
1
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(d)
iron bar would still be attracted / coil still magnetised so still works
for 1 mark each
yes + wrong answer
0 marks
yes + current still flows
1 mark
yes + still magnetised / iron bar still attracted
2 marks
2
[9]
M3.
(a)
(i)
it moves or experiences a force horizontally to the right
for 1 mark
1
(ii)
A – moves in opposite direction or force reversed e.c.f.
B – faster movement or larger force
(not move further)
for 1 mark each
2
(b)
turns clockwise
oscillates/reverses
comes to rest facing field/at 90o to field/vertically
for 1 mark each
3
(c)
number of turns or linear number density of turns current core
for 1 mark each
3
[9]
M4.
(a)
A
must be correct for reason to score
moment (due to weight) of sail is the largest
1
or
(perpendicular) distance from pivot to rope the smallest
do not accept sail is low or sail is too heavy
1
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(b)
(i)
no resultant turning moment or in a state of balance or balanced
allow clockwise moments =
anticlockwise moments
allow no resultant force
allow (forces are) balanced
allow no acceleration
do not allow forces are equal
1
(ii)
moment = 420
allow 1 mark for moment = 700 × 0.6
or
700 × a distance from diagram (1.5, 2.1, 0.9)
2
(iii)
force = 280
420 = F × 1.5
or
F=
1 mark only
if (b)(ii) obtained by a correct method (1470, 630, 1050)
2
(c)
(as wind speed increases) the force on the sail increases
accept pressure
1
aniticlockwise moment increases or moment on sail increases
1
so clockwise moment (or opposite moment) needs to increase (by increasing
the distance from the pivot)
1
[10]
M5.
(a)
(i)
X at the centre of the lifebelt
measuring from the centre of X, allow 2 mm tolerance
in any direction
1
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(ii)
any two from:
if X is on vertical line below the hanger (but not at
centre) can gain the first point only
below the point of suspension
accept ‘(vertically) below Y’
at the centre (of the lifebelt)
accept ‘in the middle’
(because) the lifebelt / it is symmetrical
or (because) the mass / weight is evenly distributed
2
(b)
Nm or newton metre(s)
accept Newton metre(s)
do not accept any ambiguity in the symbol ie NM, nM or nm
1
750
(moment) = force (perpendicular) distance (between line of
action and pivot)
or (moment) = 500 1.5 gains 1 mark
2
(c)
Quality of written communication:
for 2 of the underlined terms used in the correct context
1
any three connected points from:
low(er) centre of mass / gravity
or centre of mass / gravity will be close(r) to the wheels
/ axle / ground
(more) stable
or less unstable
less likely to fall over
accept ‘less likely to overturn’
do not accept ‘will not fall over’
the turning effect / moment (of the weight of case) is less
or so less effort is needed to hold the case
ignore references to pulling the case
so the pull on her arm is less
3
[10]
M6.
(i)
X-rays or gamma rays
for 1 mark
1
Page 23 of 29
(ii)
passes through flesh;
stopped by bone/absorbed
for 1 mark each
2
[3]
M7.
(a)
(i)
(angle of) refraction
take care not to credit ‘angle of reflection’
1
(ii)
normal
do not credit ‘horizontal’
1
(b)
either
(photographic) film
or CCD(s) (charge-coupled device(s)) / CMOS(s) (sensor(s)) / (active) pixel sensor(s)
accept ‘LDR(s)’ / ‘light dependent resistor(s)’
not lux meter
do not accept light sensor(s)
1
(c)
(i)
converging
or ‘convex’
1
(ii)
either
(0).35
or (0).4(1...)
do not give any credit for an answer greater than 1
or
7 ÷ 20 for 1 mark
or
clear evidence that appropriate measuring / counting, has been
made for 1 mark
2
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(d)
otherwise it will have no effect on the light detector
or otherwise no (real) light will fall on the light detector
or ‘a virtual / imaginary image will have no effect on the light
detector’
allow error carried forwards for ‘light detector’
allow so it can be formed on the film
1
[7]
M8.
(a)
ciliary muscle
1
cornea
1
(b)
(i)
moved further (from his eyes)
1
(ii)
rays between lens and eye converging
1
rays inside eye focus on the retina
1
(c)
any two from:
•
both use a converging lens
•
image formed is real
•
image is inverted
•
image in eye formed on retina, image in camera formed
on film / CCDs
•
amount of light entering eye and camera can be controlled
2
[7]
M9.
(a)
any two points:
do not credit features which are true of sound in general eg
longitudinal waves
•
humans cannot hear ultrasound
•
it has a very high frequency / pitch
do not credit just ‘has a high frequency / pitch’
•
above the (upper) limit for humans / above 20 000 Hz
2
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(b)
(i)
ultrasound / waves are reflected
...are bounced is insufficient, but
...echo is acceptable
1
Pulse A indicates / is the crack
Pulse B indicates / is the back (of the block or crack)
need to mention both A and B to get this mark
1
(ii)
90 (mm)
accept any answer in the range 88 – 92 (mm)
1
[5]
M10.
(a)
(ultrasound) waves reflected
accept ‘bounce off’
1
at boundary / from muscle
1
(b)
(i)
time
1
(ii)
speed of (ultrasound) waves
1
[4]
M11.
(a)
1.59
accept an answer that rounds to this
allow 1 mark for correct substitution into correct equation
ie refractive index =
2
(b)
2 lines correctly drawn from the top of the pin through the lens
allow 1 mark for each
2
position of image correct
image must be upright
1
[5]
Page 26 of 29
M12.
(a)
(i)
Image distance increases
Image size increases
Remains inverted
Remains real
for 1 mark each
2
(ii)
Image distance decreases
Image size decreases
Becomes upright
Becomes virtual
for 1 mark each
2
(b)
Move lens with respect to film
Closer for distant objects
Further for near objects
for 1 mark each
3
[7]
M13.
(i)
accept input for primary
accept output for secondary
accept
or correct transposition
1
(ii)
60
allow 1 mark for correct transformation
2
[3]
M14.
(a)
(i)
Iron
for 1 mark
1
(ii)
V/240 = 2000/10 000
V = 48
V
for 1 mark each
3
Page 27 of 29
(b)
changing current in primary causes changing (magnetic) field in core links to secondary
inducing voltage (emf) in secondary (NOT current) secondary voltage/current is alternating
for 1 mark each
4
(c)
magnetic field not changing/no electromagnetic induction because direct current
for 1 mark each
2
[10]
M15.
(a)
an alternating input / current to primary (coil)
1
which produces an alternating magnetic field
accept changing magnetic field for alternating magnetic field
if first mark point scores then ‘alternating’ not required here
1
in the (iron) core
this magnetic field links with the secondary coil
1
which induces an (alternating) voltage / p.d. across the
secondary (coil)
1
(b)
0.21
accept 0.2 or any answer that rounds to 0.21
allow 1 mark for correct equation
ie power input = power output
or
allow 1 mark for substitution into correct equation
ie 230 × Ip = 12 × 4
2
[7]
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