Are formulas given in the exam?

No. You must recall SPM Physics formulas.

Is a formula sheet given for these calculations?

No. SPM Physics (4531) provides no formula sheet, recall each formula and write units on every line.

What does the kbat band mean?

Higher-order (KBAT) items combine ideas or need rearranging before you substitute.

Can a tutor mark my working?

Yes, in a one-to-one lesson the teacher checks each line and fixes the exact step that loses marks. From RM50/hr, paid trial available.

Quantum Physics Calculations (KBAT / Higher-Order)

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

Photon energy

E = hf

Light of frequency f = 5.0 × 10¹⁴ Hz (h = 6.63 × 10⁻³⁴ J s). E = hf = 6.63 × 10⁻³⁴ × 5.0 × 10¹⁴ = 3.32 × 10⁻¹⁹ J.

Photon energy (wavelength form)

E = hc / λ

Light of wavelength λ = 6.0 × 10⁻⁷ m (h = 6.63 × 10⁻³⁴ J s, c = 3.0 × 10⁸ m s⁻¹). E = hc / λ = (6.63 × 10⁻³⁴ × 3.0 × 10⁸) / 6.0 × 10⁻⁷ = 3.32 × 10⁻¹⁹ J.

Work function

W = hf₀

A metal has threshold frequency f₀ = 4.5 × 10¹⁴ Hz (h = 6.63 × 10⁻³⁴ J s). W = hf₀ = 6.63 × 10⁻³⁴ × 4.5 × 10¹⁴ = 2.98 × 10⁻¹⁹ J.

Einstein's photoelectric equation

hf = W + ½mv²max

Photon energy hf = 5.0 × 10⁻¹⁹ J strikes a metal of work function W = 3.0 × 10⁻¹⁹ J. ½mv²max = hf − W = 5.0 × 10⁻¹⁹ − 3.0 × 10⁻¹⁹ = 2.0 × 10⁻¹⁹ J (maximum kinetic energy).

Where marks are lost

Skipping units, rounding too early, and writing only the final answer (which loses method marks in Paper 2).

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 Quantum Physics calculations

These higher-order (KBAT) problems draw on the 4 relationships in Quantum Physics. None is printed in the exam, so recall each and write its symbols with units before substituting:

E = hf, Photon energy
E = hc / λ, Photon energy (wavelength form)
W = hf₀, Work function
hf = W + ½mv²max, Einstein's photoelectric equation

A worked example, with units on every line

Using hf = W + ½mv²max (h = Planck constant (J s); f = frequency of incident light (Hz); W = work function (J); m = mass of electron (kg); v_max = maximum speed of photoelectron (m s⁻¹)):

Photon energy hf = 5.0 × 10⁻¹⁹ J strikes a metal of work function W = 3.0 × 10⁻¹⁹ J.
½mv²max = hf − W = 5.0 × 10⁻¹⁹ − 3.0 × 10⁻¹⁹ = 2.0 × 10⁻¹⁹ J (maximum kinetic energy).

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: The maximum kinetic energy of the photoelectron equals hf − W. Emission only occurs if hf ≥ W (that is, f ≥ f₀).

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)

Written by the spmphysics.com.my editorial team.· Updated 5 Sept 2026

Quantum Physics Calculations (KBAT / Higher-Order), SPM Physics