Physics 2018 HSC exam pack (archive)

Students should:

• be familiar with key physical principles such as conservation laws and laws of motion and be able to apply them in a range of contexts
• show clear cause and effect relationships when they are explaining
• convert to base SI units in calculations
• show full working including full substitution into relevant formulas
• be able to extract quantitative relationships from graphs
• be able to convey understanding of concepts through use of sketch graphs
• be familiar with the units of all relevant quantities and the relevant SI prefixes and their abbreviations
• set out answer clearly when making comparisons
• use clear labels when continuing responses in a different booklet.

Question 21

In better responses, students were able to:

• outline and compare the forces between the earth and moon in term of size and direction (a)
• calculate the weight on the earth and on the moon (b).

Areas for students to improve include:

• reading the question carefully to ensure that the answer is responding to the question asked (a)
• using calculations to support answers that ask for quantitative comparisons (b).

Question 22

In better responses, students were able to:

• indicate unambiguously the direction of motion of the disc (a)
• show clear cause and effect, related to the physical principles involved (a)
• show on the sketch graph how the period and amplitude of the induced voltage varied over time (b).

Question 23

In better responses, students were able to:

• identify specific energy changes that occurred in named parts of the cathode ray tube (a)
• use clear cause and effect to describe how the magnetic field produced by the coils effects the path of the electrons (b).

Areas for students to improve include:

• outlining the specific energy transformations instead of the kinetic behaviour of the electrons (a)
• sequencing the energy transformations to convey clear understanding (a).

Question 24

In better responses, students were able to:

• clearly identify two different safety features of high voltage lines (a)
• equate the forces between the wires to derive a mathematical relationship (b)
• apply the correct equation and make an appropriate substitution including conversion from cm to m (b).

Areas for students to improve include:

• ensuring that a method such as the right hand rule is applied to determine the current direction (b)
• using a calculator correctly (b).

Question 25

In better responses, students were able to:

• outline the electron configuration in metal conductors as a sea of delocalised electrons (b)
• distinguish between the features of conduction in metals (lattice vibrations) and superconductors (BCS theory) (b).

Areas for students to improve include:

• identifying specific benefits and limitations of conductors in the context of electrical power grids (a)
• comparing methodically similar properties in both situations that are being contrasted (b).

Question 26

In better responses, students were able to:

• clearly define an electric and gravitational field and set out similarities and differences in a succinct manner.

Areas for students to improve include:

• making similarities and differences clear in the answer
• ensuring that all the requirements of the question have been fulfilled, such as including definitions or both fields.

Question 27

In better responses, students were able to:

• convey an understanding that the ruler was to be used as a scale for the analysis of the collected images (a)
• link the effect of the error on the data to a specific feature of the projectile’s motion (a)
• use the gradient of both graphs to describe the quantitative and qualitative features of horizontal velocity and vertical velocity (b)
• use the labelled points on the time axis in calculations rather than estimated values elsewhere on the graph (b).

Areas for students to improve include:

• extracting specific information from the graphs and linking it projectile motion (b)
• selecting appropriate points when determining a gradient (b)
• using the data provided rather than assuming the value of g to be 9.8 ms^-2 (b).

Question 28

In better responses, students were able to:

• demonstrate that the change in E_p leads to the given value (a)
• apply the law of conservation of energy to find the velocity as the change in E_k is equal to the given change in E_p (b).

Areas for students to improve include:

• applying the Law of conservation of energy to a variety of contexts
• converting km to m in calculations.

Question 29

In better responses, students were able to:

• relate the movement of the photoelectrons to the potential difference applied by the battery in photocell and by the depletion zone in the solar cell (a)
• link an advance in scientific understanding such as band theory to a specific understanding of semiconductors (b)
• link an advance technology such as purification to increased use of semiconductors (b).

Areas for students to improve include:

• specifying the direction of current flow in a circuit (a).

Question 30

In better responses, students were able to:

• provide cause and effect statements that showed the effect of increased demand on individual components, rather than the system as a whole
• identify that the supply voltage remains constant with increased demand and the increased energy demand led to an increase in current.

Areas for students to improve include:

• planning the response to ensure all parts of the question are answered.

Question 32

In better responses, students were able to:

• identify specific uses that are specifically related to MRI (a)
• identify that the % reflection only depends on the difference in acoustic impedance between the two tissues and not the direction which the boundary is being crossed (b)
• correctly substitute into the two equations and manipulate the equation to solve for Z₁   (b)
• complete a quantitative analysis of the data to determine the half-life of I-124 (c)
• give reasons for I-124 being suitable as part of their justification (c)
• identify that the change in frequency of the reflected ultrasound is used to determine velocity of blood (d)
• identify that increased frequency of the reflected ultrasound indicates blood flowing toward the transducer and decreased frequency of the reflected ultrasound indicates blood flowing away from the transducer (d)
• relate the answer to the images given and focus on the production of the images rather than production of x-rays (e).

Areas for students to improve include:

• making similarities and difference clear when making a comparison
• justifying the use of something by giving reasons why it is suitable.

Question 33

In better responses, students were able to:

• correctly define parsec as a distance in terms of an annual parallax of 1 parsec (a)
• construct an appropriate diagram to support their answer (a)
• outline two limitations to ground based measurement of parallax (b)
• identify the causes of the change in luminosity (b)
• identify the period, use the graph to find the absolute magnitude and manipulate the equation to find d (b)
• relate the changes in the life cycle to the physical and chemical changes (c)
• show an understanding of a range of differences between photoelectric and photographic methods using specific examples and link the differences to increased understanding (d)
• explain how peak wavelength of Black body curve is related to temperature of stars (e)
• explain how absorption spectra of stars is related to emission spectra of elements and how we can use this to determine the chemical composition of stars (e)
• clearly outline the observations made in class of incandescent bulbs, reflected sunlight and discharge tubes using a spectroscope (e).

Areas for students to improve include:

• labelling diagrams clearly
• constructing clear links between observations made and how these relate to the information being obtained.

Question 34

In better responses, students were able to:

• list two different limitations of Bohr model and relate the transitions of electrons from higher to lower energy shells to corresponding wavelengths of photons emitted (a)
• link a conservation law to an appropriate property of the neutron and convert mass defect to released energy (b)
• produce a graph with correct axes showing that the energies of emitted beta particles ranged up to a maximum value, and
• relate the maximum E_k to the value expected by the Law of Conservation of Energy and link this apparent loss of energy to the proposed new particle (c)
• describe changes in the parent nuclei that emitted the particles identified via trails in Wilson Cloud Chamber (d)
• give a description of all the key areas (particles and forces) of the standard model and give detail on how their role is important to our understanding of how the atom works (e).

Areas for students to improve include:

• using the stimulus material to answer the question
• providing an analysis on the importance of the role of particles and forces, rather than just describing their features (e).