9781741256789 Excel Year 12 Physics Online resource 2019 PDF

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YEAR 12 PHYSICS Mark Butler Free-to-download Sample Tests with answers

Sample HSC Examination 1 Try to complete these papers as if they are the real thing. These are the instructions you need to follow in the HSC Exam:

Total marks: 100

General instructions

Section I: 20 marks Section II: 80 marks

this book.

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Sect ion I: 20 marks Attempt Questions 1–20. Allow about 35 minutes for t his section. 1

2

Sandra and John stand side by side and each throw a cricket ball horizontally from shoulder height. If the balls landed the same distance from Sandra and John, what can we deduce? A The balls must have been thrown with the same initial velocity. B If John was taller than Sandra, he must have thrown the ball with a lower initial velocity. C If Sandra was taller than John, she must have thrown the ball with a greater initial velocity. D The balls must have been in the air for the same time. A ball of mass m on the end of a string turns through a radius r as it rotates around a central rod with velocity v, as shown in Figure E1.1.

Which of the following statements best describes the energy changes that occur when an Earth satellite moves from a circular orbit of radius r to a circular orbit of radius 2r ? A The satellite’s kinetic energy halves, its potential

energy doubles and the total energy remains constant. B The satellite’s kinetic energy halves, its potential energy halves and the total energy halves. C The satellite’s kinetic energy doubles, its potential energy halves and the total energy halves. D The satellite’s kinetic energy doubles, its potential energy doubles and the total energy remains constant. 4

An electron travelling with an initial velocity u enters a uniform electric field midway between two charged plates, as described in Figure E1.2. The electron travels a horizontal distance x before colliding with the positively charged plate. (You may ignore gravity in this question.)

θ

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–

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+

u v

© Pascal Press ISBN 978 1 74125 678 9

m

r

electron

x Figure E1.2 An electron fired with velocity u midway between two parallel, charged plates

Figure E1.1 Mass on a string moving with uniform circular motion around a vertical rod

What is the angle (θ ) between the vertical rod and the string? A sin θ = v 2/r g B sin θ = mv 2/r l C tan θ = mv 2/r l D tan θ = v 2/r g

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EXCEL YEAR 12 PHYSICS

Where would the electron land if the electric field strength was increased from E to 4E ? A at x/2

at x/4 C at ( 2)x D at x/8 B

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A current I flows in each of the three equally spaced, parallel wires shown in Figure E1.3. l

C momentarily clockwise D momentarily anticlockwise 7

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L L

l

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X

l

Figure E1.3 Three parallel current-carrying wires

D Not enough information has been given for the

What is the direction of the resultant force on the wire on the lower right? A

What would happen to the torque produced by a motor if a load was applied that slowed the rate at which the motor was rotating? A The torque produced by the motor would increase. B The torque produced by the motor would decrease. C The torque produced by the motor would remain constant. change in torque to be determined.

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The details of the absorption spectra of two stars X and Y are set out in Table 1.1. Table 1.1 Spectral data for star X and star Y

X

X

F B

F X

Star X

Absorption spectrum detail Contains neutral atomic lines and weak ionic lines

Wavelength shift from line on Earth All absorption lines are shifted to shorter wavelength

Y

Contains weak atomic lines but strong ionic lines

No wavelength shift

What can we deduce about the stars from Table 1?

X

A X is moving away from the Earth and is cooler than Y.

X is moving towards the Earth and is hotter than Y. C X is moving away from the Earth and is hotter than Y. D X is moving towards the Earth and is cooler than Y. B

C

X

X

X

D

F 6

A permanent magnet is dropped through a loop of wire, as illustrated in Figure E1.4. S N

Figure E1.4 Permanent magnet dropped through a loop of wire

When viewed from above the loop, in what direction will the induced current flow in the wire as the magnet falls through the loop? A momentarily clockwise and then momentarily anticlockwise B momentarily anticlockwise and then momentarily clockwise

EXCEL YEAR 12 PHYSICS

9

If the red light used to demonstrate interference with a double slit was replaced with a blue light, how would the interference pattern change? A The maxima would move further apart if blue light was used. B The maxima would move closer together with the blue light. C The intensity of the maxima would decrease if blue light was used. D The interference pattern would turn blue but otherwise remain unchanged.

10 A light source with a frequency above the threshold

frequency was used in a photoelectric experiment. If the power of the source remained constant but the wavelength was halved, how would the photocurrent produced and maximum kinetic energy of the ejected electrons change? A The photocurrent and maximum kinetic energy would both increase. The photocurrent and maximum kinetic energy would both decrease. C The photocurrent would increase and the maximum kinetic energy would decrease. D The photocurrent would decrease and the maximum kinetic energy would increase. B

SAMPLE HSC EXAMINATION 1

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© Pascal Press ISBN 978 1 74125 678 9

F X

11 Why do stars move off the main sequence on a

Hertzsprung–Russell diagram? A An iron core forms in the star and fusion no longer

produces energy. A shell of helium forms in the star, which increases the outwards radiation pressure. C A core of helium forms in the star, which decreases the outwards radiation pressure. D Hydrogen fusion begins to occur through the p–p chain reaction. B

12 A cathode ray beam was deflected by an electric field,

as shown in Figure E1.5. In what direction must a magnetic field be applied between the charged plates to enable the cathode ray to pass through the electric field without being deflected? – – +

+ +

Figure E1.5 Cathode ray deflected by an electric field in an evacuated tube A into the page

B

C to the right

D to the left

out of the page

16 Consider a car of mass m travelling with a constant

velocity v around a corner of radius r as shown in Figure E1.6. Which of the following statements best describes the net force on the car when it is at the position shown? N W S

Figure E1.6 Car travelling at constant velocity around a corner of radius r A There is no net force on the car as it is moving with

uniform circular motion. The net force depends on the v, m and r and is directed towards the west. C The net force depends on the v, m and r and is directed towards the east. D The net force will be the sum of the centripetal force and the gravitational force acting on the car. B

17 The radiation emitted from a radioactive isotope is

passed into a magnetic field and found to be deflected as shown in Figure E1.7. What type of radioactive isotope is most likely to have emitted this radiation?

13 Bohr’s model of the hydrogen atom enabled the

ionisation energy of the ground state (n = 1) of the hydrogen atom to be related to Rydberg’s constant (R), the speed of light (c) and Planck’s constant (h). What relationship did Bohr deduce for the ionisation energy of hydrogen? A E = Rh/c B E = h/Rc C E = Rc/h D E = Rhc

© Pascal Press ISBN 978 1 74125 678 9

14 Two radioactive isotopes A and B both emit alpha

particles but B has a half-life 10 times longer than A. What can we conclude about the isotopes? A B will emit more alpha particles per second than A. B A will have a bigger radioactive decay constant than B. C The alpha particles emitted from B will be more energetic than the alpha particles emitted from A. D After one half-life, 10 times more isotopes in sample A would have decayed than in sample B. 15 Why do uranium fission power reactors produce highly

radioactive waste? A Uranium-238 is very radioactive but not fissionable.

The fission products have a high proton-to-neutron ratio. C The fission products have a high neutron-to-proton ratio. D Uranium-235 is very radioactive. B

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EXCEL YEAR 12 PHYSICS

X

B

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Figure E1.7 Radiation in a magnetic field A an isotope with a neutron-to-proton ratio that was

too high to be stable B an isotope with a very high binding energy per nucleon C an isotope with a proton-to-neutron ratio that was too large to be stable D an isotope with electrons in the nucleus 18 In a Millikan oil drop experiment, an oil droplet of

mass 1.635 mg was found to levitate in an electric field of 107 NC–1. How many electron changes were on the droplet? A 107 B 1010 C 104

D 1013

19 The black-body emission curves from two main

sequence stars P and Q were compared. Star Q was found to exhibit a maximum black-body emission at a much shorter wavelength than star P. What does this tell us about the stars? A Star P is smaller and will leave the main sequence

faster than star Q.

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r

E

Star P is smaller and will remain on the main sequence longer than Q. C Star Q is smaller and will the leave the main sequence faster than star P. D Star Q is smaller and will remain on the main sequence longer than star P. B

20 In a high-energy nuclear collision between hadrons in

a particle accelerator, dozens of new particles can be produced. These include photons, hadrons and leptons. Why are no free quarks produced? A because quarks are fundamental particles

because the energy used to separate quarks in a hadron produces more quark pairs C because quarks cannot be produced from energy D because quarks are imaginary rather than real particles B

c

23 The proton synchrotron at CERN is 628 m in

circumference and protons circulate around the synchrotron in 2.2 µs as measured from the laboratory frame of reference. a Find the velocity of the protons. (1 mark) b Compare the relativistic momentum of the proton to the Newtonian (non-relativistic) momentum at this speed. (2 marks) c What is the circumference of the synchrotron as measured from the proton’s frame of reference? (1 mark) d What is period as measured from the proton’s frame of reference? (1 mark) e

Sect ion II: 80 Marks Attempt Questions 21–33. Allow about 2 hours and 25 minutes for this section. in the spaces provided. These spaces provide guidance for the expected length of response.

Explain, qualitatively, how the satellite could be moved efficiently to a circular orbit 1500 km above the surface. (3 marks)

Explain why, even though the speed of the particle is not increasing significantly as energy is imparted to it, the strength of the magnetic field used to keep the proton moving in a circle must be continually (3 marks) increased.

24 Consider the current-carrying wires shown in Figure E1.9.

20 A

calculations.

4 cm X

21 A student turns a 50 g mass on a string in circular motion

with a radius of 0.60 m in a vertical plane, as shown in Figure E1.8. The centre of the circle was 1.8 m above ground level and the mass was rotated with a period of 0.20 s. m = 50 g

Y 50 A 30.0 cm Figure E1.9 Current-carrying wires a

Find the direction of the force on the sides marked X, Y and Z due to the wire above the rectangular loop. (3 marks)

b

Find the net force on the rectangular loop of wire (3 marks) due to the wire above it.

radius = 0.6 m

1.8 m

25 In an investigation of a DC electric motor a student

Figure E1.8 Mass on a string turning in uniform circular motion in a vertical plane a

What is the centripetal force required to keep the (1 mark) mass moving in circular motion?

What is the tension in the string at the bottom of the motion? (1 mark) c If the string broke when the mass was at the bottom of the motion, how far would it travel horizontally before it hit the ground? (3 marks) b

22 A 1200 kg satellite is placed in a circular parking orbit

500 km above the Earth’s surface. a Calculate the velocity and acceleration of the satellite. b Determine the period of the satellite.

EXCEL YEAR 12 PHYSICS

(2 marks) (1 mark)

applies different mechanical loads to the motor and a constant operating voltage, and measures the current that flows through the windings. The results the student obtained are shown in Table 1.2. Table 1.2 Results of investigation of DC motor operating at 24 V Load torque (Nm) Revolutions per minute Current (mA) 0 200 50 0.5

176

72

1.0 1.5

151 124

143 220

2.0

98

286

a

Explain in terms of back EMF why the current increases when the mechanical load on the motor is increased. (3 marks)

b

Explain how energy is conserved as the mechanical load on the motor is increased (no calculations (2 marks) required). SAMPLE HSC EXAMINATION 1

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© Pascal Press ISBN 978 1 74125 678 9

period = 0.2 s side view

Z

6 cm

26 Figure E1.10 shows a fixed electromagnet and a rotating

c

aluminium disc. electromagnet x

30 A diffraction grating is used to separate the visible

wavelengths emitted from a discharge tube containing excited hydrogen gas. a Use Bohr’s equation to calculate the wavelength of the two longest wavelength lines emitted from electron transitions that end on the n = 2 orbital. (2 marks)

y

rotating aluminium disk

Explain why the spinning disc rapidly comes to rest (3 marks) when the electromagnet is switched on. b Explain how energy is conserved when the disc is brought to rest. (2 marks) a

c

If the disc was turned when the electromagnet was switched on, would the point marked x be at a higher or lower potential than the point marked y? Explain your answer. (3 marks)

27 This question refers to the Hertzsprung–Russell

diagram shown in Figure E1.11.

Luminosity (Lstar)

106

x

104 102 1 –2

10

10–4 40 000

y 20 000 10 000 5000 Temperature (K)

10

16O 08

56Fe 26

4He 2

8

120 050Sn 238 092 U

6 4 3H 1

2

2H 1

0 0

50

100 150 Number of nucleons

200

250

Use the diagram to determine the binding energy of helium-4 and the mass defect when the nucleus is formed from its constituent nucleons. (3 marks) b Outline how the diagram can be used to predict which elements will release energy in fusion and fission reactions. (3 marks) a

Name the type of star that would be found at x and y, and compare each star’s source of energy. (2 marks) b Compare the energy source, mass and rate at which mass is converted into energy in stars marked x and z on Figure E1.11. (3 marks) c Outline the key stages of the lifecycle of a supermassive star. (4 marks) © Pascal Press ISBN 978 1 74125 678 9

the elements in the graph.

Figure E1.12 Binding energy per nucleon as a function of the number of nucleons

2500

Figure E1.11 A Hertzsprung–Russell diagram

28 Outline how electricity distribution systems use

transformers to efficiently transmit electrical energy. (3 marks)

29 De Broglie made a radical suggestion in his doctoral

thesis that had a huge influence on our understanding of atomic physics. a What was de Broglie’s hypothesis? (1 mark) b Explain how de Broglie’s hypothesis provided support (2 marks) for Bohr’s stationary state hypothesis.

EXCEL YEAR 12 PHYSICS

31 Figure E1.12 shows the binding energy per nucleon for

z

a

240

Calculate the angle of the first order (m = 1) maxima of interference for the longest visible wavelength that would be produced if the light from the hydrogen discharge tube was incident on a diffraction grating (2 marks) with 2000 lines per centimetre. c Outline three limitations of Bohr’s model of the (3 marks) atom.

b

Figure E1.10 Rotating aluminium disc and fixed electromagnet

Binding energy per nucleon (MeV)

north pole

Given that the radius of the n = 4 orbital of the Bohr hydrogen atom is r4 = 8.46 × 10–10 m, find the electron wavelength and the momentum of the electron. (2 marks)

32 a

Explain the difference between a polarised electromagnetic wave and an unpolarised wave. (2 marks)

Explain how a charged particle could be used to produce a polarised electromagnetic wave. (2 marks) c Unpolarised light of intensity I0 is passed through three consecutive polaroid filters, each with their axis of polarisation rotated by 30° with respect to the previous filter. Determine the intensity of the light after it passes through each of the filters. (3 marks) b

33 Outline the key elements of the standard model of

particle physics and explain how particle accelerators influenced the development of the model. (5 marks)

Sample HSC Examination 2 A The total energy is a maximum.

Sect ion I: 20 Marks

The total energy is a minimum. C The potential energy is a maximum. D The kinetic energy is a maximum. B

Attempt Questions 1–20. Allow about 35 minutes for t his section. 1

Projectile A is fired at an angle θ above the horizontal with an initial velocity u on a level plane. The projectile is found to have a range of x metres. A second projectile B is then fired with the same initial velocity at an angle of θ/2. What can we deduce from this information given? A Projectile A will have a greater range than projectile B. B Projectile B will have a greater range than projectile A. C The time of flight of projectile A will be greater than the time of flight of projectile B.

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