PHYSICS EXAMINATIONS – 2007 Bruce Walsh

REMINDERS  Calculators  Study design and textbooks  Examiners report  VASS system  SSMS  Exam format - detailed studies

JUNE EXAMINATION

STATISTICS  6544 students  Mean = 99 = 55%  Std dev = 41.5 = 23%  Number achieving 100% = 4

GRADE MIN (/180) MIN (%) A A13776 B B10357 C+8447 C6737 D+5229 D3821 E+2715 E2011

 Challenging  Detailed studies  Attempt ONE detailed study only  Explanations address specific question. – Diagrams  Show working GENERAL COMMENTS

 Converting units  Calculations – powers of 10 - raising to power eg. R 3 - raising to power eg. R 3 - simple mathematics - simple mathematics  Care reading scale on axes  Multiple choice questions  Illegible writing

PROBLEM AREAS MOTION  Q2 Light lands directly below seat  Q5 Determining Δp  Q9, 10 In spring formulae x is extension not total length  Q11 Total energy is constant

 Q12 Difficulty with ratios  Q13 Mathematical difficulties with R 3 and T 2  Q14,15 Treat horiz and vert components. Derived equations caused confusion

ELECTRONICS & PHOTONICS  Q1,2 Improving, but still difficult for students  Q3 Few provided a clear answer  Q9 Explanations unclear  Q10,11 Intensity of light cannot go below zero

RELATIVITY  Q2 Many unable to determine speed of sound  Q8 Determining appropriate frame of reference

MATERIALS & STRUCTURES  Q2 Torques  Q4 Locating point of tension  Q8 Work = Area of graph x Volume. Many forgot volume  Q10 Torque or triangle of forces or resolution of forces

FURTHER ELECTRONICS  Q5 Time constant – 63% change  10 Increased I  increased voltage drop OR Decreased load  decreased  and increased ripple  Q11 Regulator, increase transformer output, increase capacitor

NOVEMBER EXAMINATION

STATISTICS  6392 students  Mean = 110 = 61%  Std dev = 43 = 24%  Number achieving 100% = 14

GRADE MIN (/180) MIN (%) A A15083 B B11463 C+9251 C7441 D+5430 D3620 E+2011 E106

GENERAL COMMENTS  Accessible paper  Detailed studies  Illegible writing  Explanations must address specific question

 Explanations – one mark per point  Show working  Unit conversions, eg. cm 2 to m 2  Powers of 10 calculations  Transformation of simple equations.

 Direction of current flow  Diffraction – Light & Matter c.f. Sound  Diffraction patterns – gradual change as λ/w ratio varies

PROBLEM AREAS ELECTRIC POWER Q1,2 Sketching magnetic fields. Q1,2 Sketching magnetic fields. Q11 Series circuit ideas Q11 Series circuit ideas Q12 More power consumed than supplied Q12 More power consumed than supplied Q15 Explain application of Lenz’s law Q15 Explain application of Lenz’s law

LIGHT and MATTER  Q5, 6 Diffraction patterns  Q9 Not interference effect  Q10, 11 Behaviour of bound and free electrons

SYNCHROTRON  Q4 Application of right hand rule  Q11 Explanations poor

PHOTONICS  Q6 Snell’s law  Q7, 8 Relate effect to speed variations  Q11 Internal reflection – gradual change in amount

SOUND  Q4 Resonance will be louder  Q7 Relate graph to frequency range of human voice