Physics 2025 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

In better responses, students were able to:

• link specific radiation properties to practical testing methods with clear outlines of observational differences between alpha and beta sources
• outline expected results and identify conclusions explicitly, for example, the source whose radiation is stopped by paper is the alpha emitter
• use annotated diagrams showing experimental setup, radiation paths and expected outcomes
• focus on methodology, rather than focusing on particle properties
• select straightforward, specific methods, for example, penetration testing, magnetic/electric field deflection, cloud chamber ionisation trails
• use appropriate and precise terminology while matching the key word ‘outline’ with concise method descriptions
• structure responses clearly and concisely.

Areas for students to improve include:

• making explicit statements about observational differences that could be used to distinguish sources
• stating outcomes clearly, for example, 'alpha is stopped, beta passes through', rather than just 'test with paper'
• referring to relevant experimental methods and avoiding references to unrelated experiments such as Rutherford scattering, Chadwick's neutron discovery, diffraction
• selecting methods specifically designed for radiation identification
• providing sufficient detail in responses, rather than making general statements such as use a detector or measure ionisation.

Question 22

In better responses, students were able to:

• directly answer the question and describe energy transformations in both transformers and power transmission lines
• identify the generation of eddy currents in the iron core, transforming electrical energy into heat
• note energy losses due to incomplete flux linkage or magnetic hysteresis.

Areas for students to improve include:

• identifying the focus on energy transformations in the system correctly
• avoiding general descriptions of step‑up and step‑down transformers and their functions
• ensuring all parts of the question are answered, including energy changes in both transformers and transmission lines
• providing precise descriptions of energy losses to demonstrate deeper understanding, for example, eddy currents, incomplete flux linkage, magnetic hysteresis.

Question 23 (a)

In better responses, students were able to:

• substitute the correct values into F = BIL and τ = Fr
• convert from cm into m correctly
• identify the direction of the torque on the loop.

Areas for students to improve include:

• demonstrating understanding that the coil was not located in a magnetic field, and therefore an area could not be calculated.

Question 23 (b)

In better responses, students were able to:

• quantify factors which verify 2τ
• address the magnetic field (B) and current (I) separately to equal 2τ = IB, to show how each contributes to twice the torque.

Areas for students to improve include:

• quantifying the magnitude of current (I) and magnetic field (B) for both variables.

Question 24

In better responses, students were able to:

• use the information provided in the stimulus to answer the question
• show all working and multi-step calculations.

Areas for students to improve include:

• using fewer formulas to solve the question.

Question 25 (a)

In better responses, students were able to:

• plot data points clearly and correctly
• draw the line of best fit neatly using a ruler, and extrapolate to the x-axis to identify the threshold frequency
• read the threshold frequency correctly as 0.7 x 10¹⁵ Hz.

Areas for students to improve include:

• plotting data points clearly, for example, with crosses rather than small dots, so they are visible
• using a ruler to draw a clear and accurate line of best fit
• extrapolating the line of best fit to the x-axis to determine the threshold frequency value
• interpreting the x-axis scale correctly.

Question 25 (b)

In better responses, students were able to:

• identify the experimental features
• explain the experimental features by applying particle/quantum model of light.

Areas for students to improve include:

• engaging with the question and/or stimulus to plan a response that answers the question
• articulating the variables and hence the features of the graph correctly, that is, identifying the gradient of line of best fit s h/q.

Question 26 (a)

In better responses, students were able to

• identify the correct equations from the Formula Sheet and transcribe them into their working
• substitute accurately and provide full working to calculate the correct value.

Areas for students to improve include:

• recording data from the stimulus and the question to guide formula choice
• recognising the symbol for electromotive force (emf)
• demonstrating understanding that the average emf is a function of the flux in the starting position and finishing position and that no averaging after that is required
• showing full and clear working.

Question 26 (b)

In better responses, students were able to:

• engage with all aspects of the stimulus, that is, increased rotational speed and opposite direction
• recognise that the increased rotational speed will impact two features of the graph, that is, the number of cycles occurring in the time period and the emf (voltage)
• recognise that the starting position results in emf (voltage) starting at its greatest magnitude, rather than at zero
• sketch a graph accurately.

Areas for students to improve include:

• engaging fully with the question and stimulus to ensure a thorough response
• plotting some key guiding points, for example, maximum, minimum and intercepts, first over the span of the graph so that the sketch has some guidelines already in place.

Question 27

In better responses, students were able to:

• outline the difference between Schrödinger’s, Rutherford’s and Bohr’s models in terms of electron behaviour
• answer the question in terms of comparing Schrödinger’s to Rutherford and Bohr’s atomic models.

Areas for students to improve include:

• writing succinctly to answer the question
• focusing on the electron behaviour for each model rather than focusing on unrelated aspects of the question such as protons and neutrons
• demonstrating understanding that the question is focused on Schrödinger
• referring to Rutherford’s and Bohr’s atomic models, rather than the Rutherford-Bohr model.

Question 28

In better responses, students were able to:

• start with general algebraic formulas then derive needed expressions algebraically
• substitute numbers after the working is complete, to prevent rounding errors and make reasoning more transparent.

Areas for students to improve include:

• resolving velocity into components before using kinematics equations
• using vertical displacement correctly, that is, s = 0 m
• using sin and cos as applicable
• recognising that at the maximum height V_y = 0.

Question 29 (a)

In better responses, students were able to:

• identify that at the top of the rotation, point B, the only force acting is F_g, therefore F_g = F_c
• show algebraically how the variables can be used to derive the given value of speed at point B.

Areas for students to improve include:

• choosing correct equations and recognising that calculations are based on instantaneous forces
• showing how the variables have been rearranged or clearly substituted when deriving for v.

Question 29 (b)

In better responses, students were able to:

• identify that the object at point A is faster than the object at point B
• identify that in vertical circular motion there are energy transformations that occur as the object rotates to a higher position, transforming its E_k into gravitational potential energy (GPE)
• use the law of conservation of energy mathematically by using the equations for E_k and GPE to show what happens to the E_k as the object increases its height from r to 2r.

Areas for students to improve include:

• recognising that the object possesses both E_k and GPE at both points A and B
• providing information about the role that forces play in changing the object’s motion.

Question 30 (a)

In better responses, students were able to:

• substitute values for h, m and v into de Broglie’s equation correctly.

Areas for students to improve include:

• demonstrating the process of calculating the wavelength beyond selecting the appropriate formula or showing the provided value for wavelength
• recognising the quantum mechanical nature of electrons.

Question 30 (b)

In better responses, students were able to:

• apply trigonometry or the small angle approximation to calculate the distance between the two fringes.

Areas for students to improve include:

• selecting the appropriate integer value to signify the fringe next to the central interference fringe
• recognising prefixes and multipliers used to define units, for example, micro (μ) and nano (n)
• manipulating the equation for interference of light to find the angle to the interference fringe or the distance between interference fringes.

Question 30 (c)

In better responses, students were able to:

• equate different formulas for energy to calculate voltage using the given values.

Areas for students to improve include:

• distinguishing between the physical quantities such as voltage and velocity
• applying all mathematical functions when using a formula to calculate the value of a quantity, for example, squaring the velocity and multiplying by ½ when calculating kinetic energy
• recognising that accelerating an electron from rest to 4 × 10³ m s^-1 will increase its kinetic energy.

Question 31

In better responses, students were able to:

• interpret the question and focus on the experiments that investigated cathode rays
• link experimental results to corresponding property and existence of electrons
• use precise and specific language to describe both results and properties/existence
• assess the contribution the experimental results had on broader scientific knowledge.

Areas for students to improve include:

• analysing the question to identify and address all parts
• using precision when linking experimental results to properties/existence of electrons
• linking experimental results to the existence of the electron, not just its properties
• providing specific and descriptive examples to support their assessment.

Question 32

In better responses, students were able to:

• define special relativity in terms of Einstein’s two postulates
• structure their answers by referring to each of the three consequences outlined in the question
• provide mathematical detail or thought experiments for each consequence
• provide clear links to experimental evidence which validate the consequences predicted by Einstein.

Areas for students to improve include:

• using representations, such as diagrams and graphs to explain concepts
• sequencing answers logically to address the question
• ensuring experimental evidence refers to specific data which verifies the outlined consequences.

Question 33

In better responses, students were able to:

• describe features of particle accelerator experiment(s) accurately with clear links to the measurement of fundamental particle(s)
• link bosons as force carriers and provide examples of the boson and the force they are responsible for
• provide at least two ideas that directly relate to the Standard Model.

Areas for students to improve include:

• providing a clear description of a suitable experiment involving particle accelerators or cloud chambers for the measurement of fundamental particles
• demonstrating understanding of the importance of all three components of the Standard Model
• demonstrating understanding that the Higgs boson is not a force carrier/gauge boson.

Question 34 (a)

In better responses, students were able to:

• identify and apply the formula for speed correctly
• demonstrate accurate substitution of values and unit conversions, such as converting kilometres into metres and doubling the radius before applying the formula.

Areas for students to improve include:

• reading information provided in stimulus material to ensure they correctly identify the relevant formula
• recognising the radius must be doubled to determine the distance travelled by light
• converting units accurately, ensuring that distances given in kilometres are converted into metres and that time is expressed in seconds when calculating speed in metres per second
• substituting values into the formula correctly and presenting answers with the correct units.

Question 34 (b)

In better responses, students were able to:

• show understanding of how the radius of an elliptical orbit differs from that of a circular orbit
• demonstrate the application of the speed formula
• recognise that speed is directly proportional to the additional distance travelled, indicating understanding of how variations in orbital radius lead to changes in speed, with greater distances resulting in increased speed when time remains constant.

Areas for students to improve include:

• filtering information in the stimulus so that their responses remain focused and well-directed
• demonstrating understanding that the radius of the two models, circular and elliptical, results in extra distance that light must travel along the longer axis of the eclipse aligned with the path of light
• including annotated diagrams as part of their responses where applicable
• recognising the direct proportionality between distance and speed.

Question 35

In better responses, students were able to:

• structure their response clearly to address the two observations
• recognise that the motion of the magnet in the initial phase involved acceleration and an increase in velocity
• make clear statements of the nature of motion and the related observation on the balance
• account for the application of force through the copper tube as a consequence of Newton’s Third Law, in reaction to the force exerted on the magnet.

Areas for students to improve include:

• structuring the response in two parts, allowing for direct connection between causes, relevant physics and effects
• interpreting the stimulus carefully to inform responses that directly address the question.

Question 36

In better responses, students were able to:

• apply the law of conservation of momentum to calculate the initial velocity of m_b as 0 m/s
• derive the escape velocity formula and apply it to the initial conditions of m_a
• describe the extended motion of the two masses, that is, beyond figure 2, and how the law of conservation of energy explains the changing speed of the masses as they reach their endpoints.

Areas for students to improve include:

• targeting important parts in the question, in this case focusing the response on subsequent motion
• referring to relevant laws of conservation and using formulas to form the supporting evidence for the subsequent motion.