Physics 2023 HSC exam pack

Students should:

• read the question carefully to ensure that they do not miss important components
• have a clear understanding of the glossary of key words in the question and recognise the intent of the question and its requirements
• plan the response to assist in the logical sequencing of information
• integrate relevant scientific terms into their responses
• show clear cause and effect relationships related to key physical concepts in explanations
• engage with any stimulus material provided and refer to it in their response when required by the question
• show full working in calculations including formulas and substitution into formulas
• include correct units and directions for calculated vector quantities
• review their response to ensure that it addresses all the requirements of the question
• be familiar with the constants and formulas provided on the Data and Formula Sheets
• be familiar with the SI units of all relevant quantities and the relevant prefixes and their abbreviations
• be able to plot graphs and understand the relationship between the graph and the relevant concept
• be able to extract quantitative relationships from graphs
• 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
• be able to discuss how a range of models are applied in Physics and the evidence used to validate them.

Question 21(a)

In better responses, students were able to:

• correctly identify variables to determine luminosity.

Areas for students to improve include:

• distinguishing between the definitions for luminosity and brightness.

Question 21(b)

In better responses, students were able to:

• describe a range of features comparing Star A and Star B on an H-R diagram. For example, hydrogen fusion in Star A and no fusion in Star B.

Areas for students to improve include:

• interpreting the H-R diagram correctly and understanding complex features of stars such as fuel and size to use in comparisons.

Question 22

In better responses, students were able to:

• identify the time between the pulses is the relativistic time.

Areas for students to improve include:

• calculating the correct value for the denominator of the time dilation equation.

Question 23(a)

In better responses, students were able to:

• identify and make accurate substitutions into the correct equation for gravitational force.

Areas for students to improve include:

• using values with scientific notation in calculations. For example, 6 x 10^-7  equals 0.0000006.

Question 23(b)

In better responses, students were able to:

• identify that the longer wavelength photon had the lower energy and therefore make the appropriate calculations.

Areas for students to improve include:

• substituting into relevant equations.

Question 23(c)

In better responses, students were able to:

• report an answer in SI units.

Areas for students to improve include:

• understanding that Kelvins are the SI unit of temperature in astronomy.

Question 24(a)

In better responses, students were able to:

• equate the correct equations to determine the magnetic field required.

Areas for students to improve include:

• recognising that magnetic field is a vector quantity, therefore, direction is needed.
• understanding that Ampere’s Law is only for current in straight conductors and not for particles in a magnetic field and cannot be used in this question.

Question 25(a)

In better responses, students were able to:

• describe the function of a split ring commutator as reversing the current in the loop.

Areas for students to improve include:

• ensuring they address the key word used in the question.

Question 25(b)

In better responses, students were able to:

• explain that increased back emf will reduce the current in the motor.

Areas for students to improve include:

• distinguishing that part a and b were separate questions
• understanding that eddy currents are not the same as back emf
• identifying back emf in the motor
• showing a cause-and-effect relationship.

Question 26(a)

In better responses, students were able to:

• calculate the mass defect from the data then use this to calculate energy
• organise mathematical working showing all steps and substitution of data in a logical way
• state the relevant units for energy using either MeV or Joules.

Areas for students to improve include:

• transposing data from the table
• understanding that mass is provided in atomic mass units and it is not energy
• being aware of significant figures and the inaccuracy that results with rounding data too early.

Question 27(a)

In better responses, students were able to:

• compare emission spectra of elements to absorption spectra of stars
• describe maximum peak intensity in relation to black body radiation curve. 
   

Areas for students to improve include:

• understanding that maximum wavelength in Wiens Law is the wavelength at peak intensity
• describing how different elements have unique emission spectra and link this to how it is used to determine chemical composition. 

Question 27(b)

In better responses, students were able to:

• relate red shifted and blue shifted light to approaching and receding sides of the rotating star to explain broadened spectral line.

Areas for students to improve include:

• relating red shift and blue shift to the parts of the star that are rotating
• understanding the difference between a star's rotation on its axis and the concept of an object's revolution.

Question 28(a)

In better responses, students were able to:

• identify the correct equation and substitute the data given.

Areas for students to improve include:

• showing the equation being used and the data being substituted.

Question 28(b)

In better responses, students were able to:

• apply Ohm’s Law to the secondary circuit when a second globe is added
• apply the Law of Conservation of Energy to then deduce the effect of the change in current from the secondary coil to the primary coil.

Areas for students to improve include:

• understanding the change in current that occurs when a globe is added to a parallel circuit
• explaining the application of the Law of Conservation of Energy when a current is changed in a transformer.

Question 29

In better responses, students were able to:

• describe the unpolarised nature of the light emitted by the incandescent lamp
• explain how a component of waves not parallel or perpendicular to the polarising axis were transmitted and relate this to a reduction in intensity
• support their answers with clear diagrams.

Areas for students to improve include:

• describing the important feature of the light before and after it passes through the polariser
• explaining how the interaction of unpolarised light with the polariser results in polarised light
• including a labelled diagram.

Question 30(a)

In better responses, students were able to:

• show how the rate of change of flux through the ring determined the force between the ring and the coil.

Areas for students to improve include:

• determining the effect of the changing magnetic field on the ring.

Question 30(b)

In better responses, students were able to:

• identify that an emf is induced in ring Y, but no current will flow (i)
• calculate the emf induced in the ring for the time period that the magnetic flux was increasing (ii).

Areas for students to improve include:

• relating an electromagnetic change in the ring to the ring’s motion (i)
• substituting the correct values (including powers of 10) into a relevant equation (ii).

Question 31

In better responses, students were able to:

• apply the concept of electromagnetic induction due to the relative motion of magnets on the roller coaster and the aluminium braking fin to explain similarities and differences between the two data sets.

Areas for students to improve include:

• engaging with all parts of the graph to identify similarities and differences
• considering cause and effect to explain the features of the graph.

Question 32

In better responses, students were able to:

• determine the range by evaluating the rotational speed of the launcher and applying it as a horizontal velocity for the ball
• determine the time of flight by considering the vertical velocity
• use clear and concise diagrams or annotations/descriptions to indicate the position of the ball relative to the new launcher position.

Areas for students to improve include:

• realising there was both a horizontal motion for the ball and a rotational motion for the launcher at the same time
• being clear in labelling diagrams or describing positions, particularly including the use of angles
• ensuring clear lay out of working so it is easy to follow
• being careful with rounding in calculations too early.

Question 33

In better responses, students were able to:

• identify multiple experiments and observations which allowed scientists to increase their knowledge of both processes that occur in the physical world and properties of subatomic particles
• recount methods and use diagrams while relating these procedures to both the field particles interacted with, and the interactions with matter. A combination of Thompson, Millikan, Chadwick, Geiger Marden and particle accelerators afforded students ample opportunity to address all these points.

Areas for students to improve include:

• using diagrams in their answers deconstructing the question and addressing all parts in detail
• knowing details of key experiments including methods and outcomes.

Question 34(a)

In better responses, students were able to:

• link the conservation of energy of the satellite as it moves from P to Q with the decrease in K and increase in U (that results from radius increasing).

Areas for students to improve include:

• using conservation of energy to analyse the situation
• focusing on the P to Q part of the journey and being aware that this is after the engines are fired
• knowing that an increase in radius leads to a smaller negative U value which is an increase in U.

Question 34(b)

In better responses, students were able to:

• follow a logical problem-solving sequence incorporating all relevant energy values to reach the desired value for K at Q.

Areas for students to improve include:

• using a clear step-by-step process incorporating subscripts to ensure clarity about where the E, U and K values are being determined
• showing full working with equation, substitution and answer unrounded.

Question 34(c)

In better responses, students were able to:

• use physics principles appropriately supported by calculations to provide the ‘how’ and ‘why’ for a specific motion of the satellite passes Q.

Areas for students to improve include:

• showing a cause-and-effect relationship
• understanding the potentially sequential nature of questions and therefore referring back to parts (b) and (c) 
   
• using physics principles and numerical values to support responses.