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# PHYSICS EXAMINATIONS – 2006 - PowerPoint PPT Presentation

PHYSICS EXAMINATIONS – 2006. Bruce Walsh. REMINDERS. Calculators Study design and textbooks Examiners report VASS system SSMS. JUNE EXAMINATION. STATISTICS. 6712 students Mean = 90 = 50% Std dev = 38.7 = 21.5% Number achieving 100% = 0. GENERAL COMMENTS.

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PHYSICS EXAMINATIONS – 2006

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## PHYSICS EXAMINATIONS – 2006

Bruce Walsh

### REMINDERS

• Calculators

• Study design and textbooks

• Examiners report

• VASS system

• SSMS

## JUNE EXAMINATION

### STATISTICS

• 6712 students

• Mean = 90 = 50%

• Std dev = 38.7 = 21.5%

• Number achieving 100% = 0

• Reasonably challenging paper

• Detailed studies

• Attempt ONE detailed study only

• Explanations address specific question. – Diagrams

• Show working

• Converting units

• Calculations – powers of 10

- raising to power eg. R3

• Care reading scale on axes

• Multiple choice questions

• Illegible writing

### PROBLEM AREASMOTION

• Q3. Two stage – get acc from F=ma then use const acc formula. Many assumed a=9.8. Few used W=ΔEK

• Q6. Net force. Many neglected gravity. Others added it instead of subtracting

• Q7. Multiple steps. Net force const. Use F=ma for acc then const acc for dist. OR I=Δp for speed then const acc for dist. Many assumed acc was g

• Q8. Two components then Pythagoras. Multiple steps

• Q11. I=Δp or get acc then f=ma Easier to treat space station than shuttle (3rd law). Confusion over masses and speeds

• Q12. Conservation of energy. Some fudging

• Q14. Conservation of energy. Loss of Grav PE = Gain in Spring PE. Many used F=-kx assuming f=mg at bottom

### ELECTRONICS & PHOTONICS

• Q1. DC biasing. Parts 2 and 3 poorly done

• Q3. Signal voltage - clipping

• Q4. Decoupling capacitor. Most knew what it did but not why

• Q8. Modulation

### RELATIVITY

• Q7-9. Confusion over frames of reference.

### MATERIALS & STRUCTURES

• Q3. Reading axis ε=2% not 2

• Q4. Calculated wrong material or misread strain axis

• Q6. Work = Area of graph x Volume Many forgot volume or had calculation difficulties

### FURTHER ELECTRONICS

• Q7. Operation of regulator

## NOVEMBER EXAMINATION

### STATISTICS

• 6589 students

• Mean = 111 = 62%

• Std dev = 41 = 23%

• Number achieving 100% = 20

• Accessible paper

• Detailed studies

• Illegible writing

• Explanations must address specific question

• Explanations – one mark per point

• Show working

• Unit conversions, eg. cm2 to m2

### PROBLEM AREASELECTRIC POWER

Q1. Sketching magnetic fields.

Q8. E.M. induction. Trouble calculating area (units) and getting correct time

Q14-15. Operation of transformer

Q16. Overall distribution system

### LIGHT and MATTER

• Q1. Incoherent light from wide spectrum sources. Confused with discrete emission spectrum.

• Q2. Wave and particle predictions for PE effect.

• Q6. Meaning of standing waves for electrons in stable states in atoms.

• Q11. Distinction between matter and electromagnetic radiation. Wrong Planck’s constant. Assumption that because momentum was the same, energy was also. Electron speed taken as 3x108.

### SYNCHROTRON

• Q5. Relate greater wavelength to reduced energy.

### PHOTONICS

• Q5. Operation of graded index multimodal fibres

• Q6-7. Snell’s law

• Q10. Rayleigh scattering increases as wavelength decreases.

### SOUND

• Q6. Sound from front and rear out of phase, box prevents interference.

• Q9. Unable to explain resonance in terms of behaviour of sound waves.