Download MIDPHY15_EXAM

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Centre Number
Student Number
2015
HIGHER SCHOOL CERTIFICATE
MID-YEAR EXAMINATION
Physics
General Instructions
Total marks - 75
 Reading time – 5 minutes
This paper has two parts, Part A and Part B
 Working time – 2 hours
Part A – 20 marks
 Attempt Questions 1-20
 Allow about 35 minutes for this part
 Write using black or blue pen
 Draw diagrams using pencil
Part B – 55 marks
 Attempt Questions 21-30
 Allow about 1 hour and 25 minutes for this
part
 Use the multiple-choice answer sheet
provided
 Write your Centre Number and Student
Number at the top of this page, page 8,
and on the multiple-choice answer sheet
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.
MIDPHY15_EXAM
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2015 HIGHER SCHOOL CERTIFICATE
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
An astronaut stood on bathroom scales on earth and recorded a reading of 110 kg. The
same astronaut then went to planet X and recorded a reading of 80 kg. What is the
acceleration due to gravity on planet X?
(A)
1.38 ms-2
(B)
7.13 ms-2
(C)
13.5 ms-2
(D) 110 ms-2
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2
Students used a pendulum with mass m, string length L, and launch angle to
calculate the acceleration due to gravity. Which of the following correctly represents
the relationship measured for the period of a pendulum?
(A) T  L
(B) T  1/L
(C) T2 L
(D) T  m
3
Students compared the flight of a paper plane and a ball thrown across the room.
Why will the equations for projectile motion not be accurate in predicting the path of
the paper plane?
(A) A paper plane has almost no mass.
(B) A paper plane is not accelerated by gravity like the ball.
(C) A paper plane is acting like an unpowered object.
(D) A paper plane is acting like powered object.
4
A small pebble is dropped from a height and falls for 2.3 seconds. What was the
height of drop?
(A) 11.3 m
(B) 16.1 m
(C) 25.9 m
(D) 51.8 m
5
Students carried out an experiment involving spinning around a cork at the end of a
string in order to measure circular motion. How should students record the risk and
precaution in this case?
(A) Projectile hazard: be careful.
(B) Projectile hazard: stand back 1 m from spinning cork.
(C) Motion hazard: stop the cork from spinning fast.
(D) Cork hazard: do not use a spinning cork.
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6
What occurs to the value of R3/T2 for the planets in our solar system as we move out
from Mercury top Neptune?
(A) The value will increase.
(B) The value will decrease.
(C) The value will fluctuate.
(D) The value will remain constant.
7
Which of the following is an equivalent statement of Einstein’s Principle of
Relativity?
(A) No experiment can be performed to determine the absolute motion of an object.
(B) No experiment can be performed to determine the speed of light relative to a
moving observer.
(C) All motion is relative.
(D) Light does not need a medium of propagation.
8
A student moves a magnet near a coil of wire with a few loops. There is a
galvanometer attached across the ends of the coil. Which of the following correctly
describes the action and the consequence on the voltage read by the galvanometer?
(A) Increasing the motion of the magnet will decrease the voltage.
(B) Increasing the number of loops in the coil will decrease the voltage.
(C) Decreasing number of loops in the coil will decrease the voltage.
(D) Decreasing the strength of the magnet will increase the voltage.
9
A rectangular coil made of one piece of wire on an axle turns in between rectangular
pole pieces. The coil measures 10 cm along the turn axis and is 16 cm wide.
What is the torque acting on this coil if a current of 2.6 A is flowing and the field
strength is 0.045 T where the coil turns?
(A) 9.36 x 10-4 Nm
(B) 1.87 x 10-3 Nm
(C) 0.0117 Nm
(D) 18.72 Nm
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10 What is the role of the commutator in a DC electric motor?
(A) It switches the direction of the current in the coil every ½ turn of the rotor.
(B) It switches the direction of the current in the external circuit every ½ turn of the
rotor.
(C) It switches the direction of the current in the coil every ¼ turn of the rotor.
(D) It keeps the current in the coil travelling in the same direction as the rotor turns.
11 Students were moving a long loop of wire through the air and noted that a small
fluctuating voltage occurred across the ends of the wire. Why did this happen?
(A) Eddy currents caused the wire to heat up.
(B) An emf was induced when the wire cut across the Earth’s magnetic field lines.
(C) An magnetic field is in induced when charges move in the wire.
(D) An emf was induced when the wire moved parallel to the Earth’s magnetic field
lines.
12 The diagram represents two different regions of magnetic field.
How does the flux in region X compare with the flux in region Y?
(Note: The diagram is to scale.)
region X
region Y
X
X
X
X
X
X
X
X
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

X
X
X
X
(A) The flux in X is into the page, and greater than the flux in Y.
(B) The flux in X is out of the page, and greater than the flux in Y.
(C) The flux in X is out of the page, and less than the flux in Y.
(D) The flux in X is into the page, and equal to the flux in Y.
MIDPHY15_EXAM
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13
A transmission line is set up to take electricity to a new suburb. What happens to the
resistance losses when the thickness of the transmission line is increased and all other
factors remain the same?
(A) The resistance losses will decrease.
(B) The resistance losses will not be affected.
(C) The resistance losses will increase.
(D) The resistance losses are independent of wire thickness.
14
Which of the statements below is valid regarding how real voltage transformers work
in a power grid?
(A) The input electrical energy is equal to the output electrical energy.
(B)
The input electrical energy is converted into mechanical energy.
(C)
The input electrical energy is converted into heat energy and a lower amount of
output electrical energy.
(D) The input electrical energy is converted into heat energy, and the amount of output
electrical energy can be higher or lower than the input electrical energy.
15 Thompson carried out early experiments with a cathode ray tube. Why did he make the
cathode rays travel into a region of crossed electric and magnetic field inside the tube?
(A) This forced the cathode rays to be deflected.
(B) This alone allowed him to calculate the velocity of the cathode rays moving in a
straight line.
(C) This alone allowed him to calculate the charge of cathode rays.
(D) This alone allowed him to calculate the charge to mass ratio of the cathode rays.
16 Students observed gas discharge tubes at different pressures and noticed that the tube
with the lowest pressure did not show much of a light display, producing only a faint
green glow. What is the correct explanation for this?
(A) At low air pressure there is not enough gas atoms in the tube for fluorescence,
and the cathode rays fluoresce upon hitting the glass.
(B) At low air pressure there are too many gas atoms in the tube to fluoresce, while
the green glow come from cathode rays hitting the glass.
(C) The cathode rays become light rays and then fluoresce upon hitting the glass.
(D) The cathode rays become UV rays and then fluoresce upon hitting the glass.
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17 What did Hertz discover in his early experiments that involved the photoelectric effect?
(A) Electromagnetic waves are transverse waves.
(B) UV light shining on the cathode will increase the photocurrent.
(C) UV light shining on the spark gap will increase the sparking.
(D) Radio waves impinging on the spark gap will cause UV light to be emitted.
18 A semiconductor was made with a band gap of 2.53 eV. What wavelength of light will
cause the electrons in the semiconductor to jump from the valence band to the conduction
band?
(A) 880 nm
(B) 675 nm
(C) 559 nm
(D) 490 nm
19 Which of the following is not a property of a thermionic diode?
(A) The device will operate with almost no warm up.
(B) The device is brittle.
(C) The device becomes very warm during operation.
(D)
The device can rectify a current.
20 What happens to the magnetic field of a magnet brought near a superconductor?
(A) The magnetic field lines will not enter the superconductor and so they stop at
the superconductor.
(B)
The magnetic field lines will not enter the superconductor and so they re-align
around the superconductor.
(C) The magnetic field lines will enter the superconductor and pass through.
(D) The magnetic field lines will enter the superconductor and stop in the middle.
MIDPHY15_EXAM
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2015 HIGHER SCHOOL CERTIFICATE
MID-YEAR EXAMINATION
PHYSICS
Centre Number
Student Number
Part B – 55 marks
Attempt Questions 21-30
Allow about 1 hour and 25 minutes for this part
Answer the questions in the spaces provided. The spaces provide guidance for the expected
length of response.
Extra writing space is provided on pages 18-20. If you use this space, clearly indicate which
question you are answering.
Show all relevant working in questions involving calculations.
Question 21 (7 marks)
A canon ball is fired at an initial speed of 42 ms-1 at an angle of 50° to the horizontal. The
ball lands at the same horizontal level from which it is fired at.
(a)
Calculate the initial vertical and horizontal component of velocity for the cannon
ball.
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(b)
Calculate the maximum height of the cannon ball.
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MIDPHY15_EXAM
Question 21 continues over the page
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Question 21 (continued)
(c)
Marks
Calculate the velocity of the canon ball 3 seconds after launch.
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(d)
State where along the path the velocity of the cannon ball is at its maximum.
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Question 22 (5 marks)
Galileo completed many experiments on motion. In one experiment, he is reported to have
dropped two masses, which were the same size but of different weight, from the leaning tower
of Pisa.
(a) Explain the result of this experiment.
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(b) Explain how the result above would differ if the balls were the same size but one was
made of foam (rough surface) and the other of metal (smooth surface).
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Question 23 (7 marks)
Satellite A is put into orbit around planet Xena. Planet Xena has a moon called Tina, which is
less than half the mass of Xena, and satellite B is put into orbit around Tina.
The mass of Xena = 5.1 x 1024 kg .
(a) Explain what the period of satellite A depends on according to Kepler’s 3rd law.
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(b) Calculate the orbital radius and the orbital speed of satellite A if it has a period of 6 hours.
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(c) Satellite B has the same orbital period as satellite A. Would the orbital radius of satellite B
be larger, the same as, or smaller than the orbital radius of satellite A? Justify your
response.
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(d) Outline how the orbital speed of satellite A would be affected if it split into two equal
sized pieces orbiting at the initial altitude.
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Question 24 (3 marks)
A space ship is travelling at 98% the speed of light. An astronaut on board the rocket measures
10 seconds for the time taken for her cat to walk across the room.
(a) Is there an experiment that the on board astronaut can do to be able to measure the
rockets’ absolute velocity relative to a stationary ether? Justify your response.
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(b) Calculate the time taken for the cat to walk across the room according to a stationary
outside observer.
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Question 25 (6 marks)
A length of copper wire is part of a simple circuit with a lamp and a battery and a switch. The
copper wire is then placed in between the poles of a strong magnet and released.
(a) Explain why the copper wire will not move when the switch is open, even though it is
near the magnetic poles, but will move when the switch is closed.
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(b) The side view diagram below shows the wire between the magnet poles. There is a
current of 3.9 A in the wire, and the wire is 12 cm long inside a uniform 55 mT magnetic
field. State the magnitude and direction of the force from the magnetic field.
N
S
I
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Question 26 (7 marks)
An early electricity pioneer set up a circuit with a voltage source and a solenoid coil and a
switch. He then set up a circuit nearby that had a solenoid coil but no voltage source, with a
magnetic compass placed near the solenoid. He noticed that the compass needle would move
and flicker when the switch was constantly changed from on to off.
(a) Identify the early electricity pioneer who carried this out, and state what the effect
became known as.
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(b) Account for the observation.
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(c) Outline what the experimenter should do in order for the results here to become accepted
by the scientific community.
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Question 27 (6 marks)
Use a table to compare the AC coil motor with the AC induction motor in terms of structure,
benefits and drawbacks.
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Question 28 (7 marks)
Thompson carried out many experiments involving cathode ray tubes that were at a low
pressure. He connected an induction coil across the ends of his cathode ray tubes.
(a) Outline why he used an induction coil in these experiments.
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(b) Explain what occurred when he arranged for the cathode rays to pass through the middle
of the region with electric plates, where the large positive plate was below and the large
negative plate was above.
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(c) Later on, scientists developed a cathode ray tube with small holes in the cathode. They
noticed that rays were passing through the holes, travelling in the opposite direction to
the cathode rays, and these were named canal rays. What can be inferred about the
properties of canal rays?
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Question 29 (4 marks)
A diagram of the semiconductor diode is drawn below.
p-type
n-type
Input
Output
+V
-V
(a) Outline how the n-type and p-type semiconductor are made mentioning the elements
involved.
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(b) Explain how the p-n junction acts when in forward bias, as shown.
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Question 30 (3 marks)
Superconductors have a lot of promise in many different fields. Assess the use of high
temperature superconductors in electric motors.
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Part B extra writing space.
If you use this space, clearly indicate which question you are answering.
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Part B extra writing space.
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Part B extra writing space.
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BLANK PAGE
MIDPHY15_EXAM
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Centre Number
Student Number
PHYSICS – MULTIPLE-CHOICE ANSWER SHEET
ATTEMPT ALL QUESTIONS
Question
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A
B
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D
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3
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20
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