How to approach
Higher-order questions apply the formula to a described situation and ask you to explain or justify. Structure your answer: state, calculate, then interpret.
The method
- List what is given, with units.
- Choose the formula and rearrange for the unknown.
- Substitute with units on every line.
- Round to the correct significant figures.
Worked examples
Where marks are lost
Practise these
Try each formula above with your own numbers, showing every line. Bring anything you get stuck on to a one-to-one lesson.
Formulas you use for Waves calculations
These higher-order (KBAT) problems draw on the 3 relationships in Waves. None is printed in the exam, so recall each and write its symbols with units before substituting:
- v = fλ, Wave speed
- T = 1 / f, Period and frequency
- λ = ax / D, Interference of waves
A worked example, with units on every line
Using λ = ax / D (λ = wavelength (m); a = slit separation (m); x = fringe separation (m); D = distance from slits to screen (m)):
Slits a = 0.5 mm apart, fringes x = 2.0 mm apart, screen at D = 2.0 m.
λ = ax / D = (5.0 × 10⁻⁴ × 2.0 × 10⁻³) / 2.0 = 5.0 × 10⁻⁷ m.
Where the marks are, and the common mistakes
In Paper 2, calculation marks are awarded line by line: the formula, the substitution with units, and the final answer with its unit and sensible significant figures. Watch this trap: Do not swap a (slit separation) with x (fringe separation).
Convert all distances to metres before substituting. For higher-order (KBAT) items, expect multi-step problems that combine two relationships or ask you to rearrange before substituting.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)