Download Yr 12 Mid Year Exam 2013

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Centre Number
Student Number
2013
HSC MID-YEAR EXAMINATION
Physics
General Instructions
Total marks - 75
 Reading time – 5 minutes
 Working time – 2 hours
This paper has two parts, Part A and Part B
 Write using black or blue pen
Part A – 20 marks
 Attempt Questions 1-20
 Allow about 35 minutes for this part
 Draw diagrams using pencil
 Use the multiple-choice answer sheet
provided
Part B – 55 marks
 Attempt Questions 21-29
 Allow about 1 hour and 25 minutes for this
part
 Write your Centre Number and Student
Number at the top of this page, page 8,
and on the multiple-choice answer sheet
(page 19)
Disclaimer
Every effort has been made to prepare this Examination in accordance with the Board of Studies documents. No guarantee or warranty is made or
implied that the Examination paper mirrors in every respect the actual HSC Examination question paper in this course. This paper does not constitute
‘advice’ nor can it be construed as an authoritative interpretation of Board of Studies intentions. No liability for any reliance, use or purpose related to
this paper is taken. Advice on HSC examination issues is only to be obtained from the NSW Board of Studies. The publisher does not accept any
responsibility for accuracy of papers which have been modified.
MIDPHY13_EXAM
1
2013 HSC MID-YEAR EXAMINATION
PHYSICS
Part A – 20 marks
Attempt Questions 1-20
Allow about 35 minutes for this part
Use the multiple-choice answer sheet provided for Questions 1-20
Select the alternative A, B, C or D that best answers the question. Fill in the response oval
completely.
Sample
2 + 4 = (A) 2
(B) 6
(C) 8
(D) 9
A
B
C
D
If you think you have made a mistake, put a cross through the incorrect answer and fill in the
new answer.
A
B
C
D
If you have changed your mind and have crossed out what you consider to be the correct
answer, then indicate this by writing the word correct and drawing an arrow as follows:
correct
A
1
B
C
D
The acceleration due to gravity on the moon Titan is about one-seventh the value on
Earth. What is the mass of an object that has a weight of 55N on the moon Titan?
(A)
7.86 kg.
(B)
39.3 kg
(C)
55 kg.
(D)
385 kg.
MIDPHY13_ EXAM
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2
If scientists’ constructed a long tunnel that goes all the way to the centre of the earth, what
would they measure about the change in gravitational field strength g as they went from
the surface down to the planet centre?
(A) g would remain about constant.
(B) g would increase.
(C) g would decrease and become zero.
(D) g would fluctuate continuously.
3
Which of the following would not occur in a re-creation of Newton’s canon ball
experiment, as the firing velocity of the canon is increased?
(A) The gravitational acceleration decreases.
(B) The range of the ball increases.
(C) The air resistance increases.
(D) The radius of the arc through the air increases.
4
A student throws a basket ball. What device will allow the most accurate readings of the
velocity of the basketball moving through the air to be calculated?
(A) A stop watch and a tape measure.
(B) A pendulum and a stopwatch.
(C) A radar gun.
(D) A motion sensor and data logger.
5
Which of the following situations involves an object travelling as though it were in an
inertial frame of reference?
(A) An ice hockey puck sliding along the ground.
(B) A toy car rolling along a smooth flat table top.
(C) A ball hit into the air by a cricket bat.
(D) A satellite orbiting the earth.
MIDPHY13_ EXAM
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6
A space ship is gradually slowing down as it travels from planet X to planet Y so that at
planet X it is travelling at 0.99 C and at planet Y it is Travelling at 0.90c. The astronaut
makes measurements of the distance between the planets, XY, when passing planet X and
when passing planet Y. What occurs with the astronauts’ measurement of XY at X and at
Y?
(A) XY is shorter at X than at Y.
(B) XY is shorter at Y than at X.
(C) XY is the same at X and at Y.
(D) XY is varying in a way that cannot be determined.
7
Which of the following is evidence for time dilation?
(A) Two initially synchronised atomic clocks that are flown on an airplane will
eventually lose their synchronisation.
(B) Two initially synchronised atomic clocks placed at opposite ends of a train
carriage will appear to hit the hour at the same time according to an onboard observer
but appear unsynchronised to an external observer.
(C) Muons travelling at near light speed appear to have a lifetime that is shorter than
stationary muons.
(D) Muons travelling at near light speed appear to have a lifetime that is longer than
stationary muons.
8
A wire has an AC current running through it. What happens to the force acting on a
stationary +1C charge placed near the wire?
(A) The force will vary sinusoidally from +Fmax to -Fmax .
(B) The force will increase from zero to +Fmax .
(C) The force will vary sinusoidally from +Fmax to zero.
(D) The force is zero.
MIDPHY13_ EXAM
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9
What is the torque on a rectangular coil that measures 5 cm x 30 cm if a force of 4 N is
acting on each of the 5cm long arms, producing clockwise rotation?
(A) 0.60 Nm.
(B) 1.20 Nm.
(C) 2.40 Nm.
(D) Zero.
10
What is the main function of the split ring in a coil motor?
(A) It conducts the current.
(B) It switches the current every complete rotation of the coil.
(C) It provides a friction less contact to the external battery.
(D) It switches the current every half rotation of the coil.
11
An AC motor and a similar size DC motor are examined. How does the AC motor and
the DC motor compare?
(A) The AC motor has more torque than the DC motor when working.
(B) The DC motor has a preferred speed, while the AC motor can spin over a range
of different speeds.
(C) The AC motor has a preferred speed governed by the input frequency, while
the DC motor can spin over a range of different speeds.
(D) The AC motor works using induction while the DC motor works using the
motor effect.
12
A thin 0.02 kg rod that is 10 cm long is placed so that it sits horizontally in a magnetic
field as shown in this side view diagram. The rod has 2.6 A passing through it in a
direction into the page and it is free to move up or down.
What is the magnitude and direction of the magnetic field needed to keep the rod from
moving up or down?
X Iin = 2.6 A
(A) 0.26 T left.
(B) 0.196 T right.
(C) 0.75 T left.
(D) 0.75 T right.
MIDPHY13_ EXAM
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B
13
An AC generator burns gas in a turbine to produce power. What is the energy conversion
occurring here?
(A) chemical energy  heat energy  kinetic energy  electrical energy
(B) chemical energy  kinetic energy  electrical energy  chemical energy
(C) heat energy  chemical energy  kinetic energy  electrical energy
(D) kinetic energy  chemical energy  heat energy  electrical energy
14
What is the resistance of a power line that is 2 km long carrying a current of 0.2 A at a
voltage of 150 000 V?
(A) 1.33 x 10-6 Ohms.
(B) 750 000 Ohms.
(C) 1.5 x 109 Ohms.
(D) cannot be determined from this information.
15
What happens to the band gap and to the conductivity of a silicon crystal as the number
of Aluminium dopant atoms increase?
(A)
(B)
(C)
(D)
16
Band gap
Increases
Increases
Stays the same
Stays the same
Conductivity
Increases
Decreases
Increases
Decreases
Which of the following is an example of a high temperature superconductor?
(A) Fe, Iron.
(B) YBCO, yttrium barium copper oxide.
(C) Hg, Mercury.
(D) Ge, Germanium.
MIDPHY13_ EXAM
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17
A stream of  particles (charge +2) travelling at a set speed is injected into a magnetic
field directed into the page as shown. Which is the best description of the motion of the
alpha particle in the field?
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
(A) The  particles continue to move in a straight line.
(B) The  particles curve down the page, moving at a constant speed.
(C) The  particles curve up the page, moving at a constant speed.
(D) The  particles curve up the page, moving at an increasing speed.
18
What is the force acting on an electron moving in between two charged plates that are
3 cm apart and that have 450 V across them?
(A) 2.4 x 10-15 N.
(B) 7.2 x 10-17 N.
(C) 2.4 x 10-17 N.
(D) 15 000 N.
19
Which of the following does not occur inside a superconductor when it is below the
critical temperature?
(A) Currents flow with zero resistance.
(B) The charges move in pairs.
(C) The lattice ceases to exist.
(D) The internal magnetic field is zero.
20
In the photoelectric effect, what happens to the measured speed of an electron emitted
from a metal surface as the frequency of the incident light is decreased?
(A) The speed increases.
(B) The speed decreases.
(C) The speed stays constant.
(D) The speed varies randomly.
MIDPHY13_ EXAM
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2013 HSC MID-YEAR EXAMINATION
PHYSICS
Centre Number
Student Number
Part B – 55 marks
Attempt Questions 21-29
Allow about 1 hour and 25 minutes for this part
Answer the questions in the spaces provided.
Show all relevant working in questions involving calculations.
Question 21 (5 marks)
Marks
An astronaut stood on normal bathroom scales on earth and noted a reading of 84 kg. The
astronaut then brought the same bathroom scales to planet X where the scales read 32 kg.
(a)
Calculate the weight of the astronaut on Earth.
1
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(b)
Calculate the mass and the weight of the astronaut on planet X.
2
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(c)
Explain whether the bathroom scales are measuring mass or weight.
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MIDPHY13_ EXAM
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2
Question 22 (7 marks)
Marks
The Michelson-Morley experiment is important in the history of Physics.
(a)
State why the result was called a ‘null result’.
2
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(b)
The diagram below shows a model of a Michelson interferometer with an ether wind.
(i) Identify which light beam(s) will produce the interference pattern.
2
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(ii) Explain how the speed of light beams a, b and c in the diagram here are
affected by the ether wind, assuming that the ether exists and that it is the
medium for light.
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MIDPHY13_ EXAM
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3
Question 23 (6 marks)
Marks
A large 2 000 kg rock is in a circular Low Earth Orbit around the earth. A small 120 kg
satellite is initially placed in the same circular orbit but about 50 m behind the rock.
(a)
Calculate the period of the rock if its orbital radius is 9 000 km and the mass of the
earth is 6x1024 kg.
1
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(b) What will occur to the orbital period of the two objects after some time, and will they
tend to change how far apart they are? Explain your answer.
3
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(c)
Are both objects in free fall? Justify your answer.
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MIDPHY13_ EXAM
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2
Question 24 (6 marks)
Marks
A bar magnet about to be dropped through a coil. The coil is in a series circuit with a
galvanometer and a small LED (light emitting diode).
(a)
Describe what occurs to the magnetic flux across the coil as the magnet drops through.
2
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(b) Explain how the galvanometer and the LED respond to the dropping magnet.
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MIDPHY13_ EXAM
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4
Question 25 (8 marks)
Marks
A 20 cm x 30 cm rectangular coil of 25 turns is constructed that is free to spin about its long
(30 cm) axis. The coil is put between the poles of a magnet as shown. The contacts to the
external battery are at points X and Y.
(a)
State the direction the coil will turn if contact X is the positive terminal, and justify
your answer.
1
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(b) Identify the type of commutator needed if the power supply to this coil is AC and
explain your reasoning.
2
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(c)
Calculate the force on the top arm of the coil if the magnetic field strength is 0.13 T, a
current of 2.6 A runs through the coil.
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MIDPHY13_ EXAM
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2
Marks
Question 25 (continued)
(d)
Calculate the torque on the coil.
1
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(e)
Explain whether or not there is back emf in this coil once it is spinning at a constant
rate.
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MIDPHY13_ EXAM
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2
Question 26 (5 marks)
Marks
Describe how you carried out an experiment to observe how an induction motor operates.
Make sure to mention the effect of changing TWO variables on the results and the
measurement instrument used.
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MIDPHY13_ EXAM
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Question 27 (7 marks)
Marks
A particle q with charge -2e is travelling from a cathode to anode inside the vacuum tube
shown below. There are charged plates set up at X and Y.
X
q
Cathode
Anode
Y
(a)
Outline the motion of q if there is no voltage across the plates XY.
1
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(b)
Explain how the motion of q is effected if a voltage of 20 000 V is put across XY, with
X positive.
2
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(c)
Calculate the electric field from XY given that 24 000 V is put across XY and the plate
separation is 18 cm.
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MIDPHY13_ EXAM
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2
Marks
Question 27 (continued)
(d)
q is travelling at 7 x 105 ms-1 . The experimenter then produces a uniform magnetic
field B that is perpendicular to the electric field in such a way that makes q travel in a
straight line between the electric plates. Calculate the required B that achieves this.
2
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Question 28 (6 marks)
In the early 20th Century Planck was a pioneer in Physics, and Einstein was his younger friend.
(a)
Outline how Planck used theory and experiment in his work with Black Bodies.
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(b) Explain how Einstein’s work with the photoelectric effect built on Planck’s work.
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MIDPHY13_ EXAM
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4
Question 29 (5 marks)
Marks
A crystal of pure silicon is grown in a vapour deposition lab.
(a)
Compare the band structure of the silicon with the band structure of aluminium. Use a
diagram to help you.
3
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(b) State how adding aluminium atoms to silicon crystal while it is growing effects the
electrical properties of silicon and justify your conclusion.
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MIDPHY13_ EXAM
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2
BLANK PAGE
MIDPHY13_ EXAM
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Centre Number
Student Number
PHYSICS – MULTIPLE-CHOICE ANSWER SHEET
ATTEMPT ALL QUESTIONS
Question
MIDPHY13_ EXAM
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A
B
C
D
2
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3
A
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4
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