Arguing that using a copper cup is justified in heat transfer measurements because copper conducts heat faster.

State that copper is a good conductor of heat, which would significantly increase heat loss to the surroundings by conduction, making polystyrene (a good insulator) a much better choice to minimize errors.

Assuming the tension in the string is exactly equal to the weight of the hanging mass when the system is accelerating downwards.

Apply Newton's Second Law: because the hanging mass accelerates downwards, there must be a net downward force, meaning weight must be greater than tension (\( mg - T = ma \)). Therefore, tension \( T \) is smaller than weight.

Assuming a gas cylinder can completely empty its gas contents into external containers/balloons.

Remember that once the pressure inside the cylinder drops to equal the ambient pressure (e.g., seabed pressure or atmospheric pressure), no more gas can flow out. The volume of gas remaining in the cylinder is still \( V \) at that ambient pressure.

Believing that eddy currents can only be induced in magnetic metals like iron, rather than any conductor.

Explain that eddy currents are induced in any metallic conductor (such as copper or aluminium sheets) experiencing a changing magnetic flux, in accordance with Faraday's Law and Lenz's Law.

Using macroscopic arguments instead of kinetic theory to explain pressure changes in gases.

Always describe the microscopic behavior: state that pressure is due to molecules colliding with the walls, and link pressure changes to the average kinetic energy (speed) of molecules and their collision frequency per unit area.

Omitting the negative sign in potential energy calculations when solving kinematics via conservation of energy.

For gravitational potential energy in orbits, use \( U = -\frac{GMm}{r} \) and carefully evaluate the difference: \( \Delta U = U_f - U_i \). Keep track of double negatives.

HKDSE · เคล็ดลับการสอบ

Physics เคล็ดลับการสอบ

Master the HKDSE Physics exam with crucial study strategies, evidence-based common mistakes analysis, and professional calculator program setups based on 2021-2025 past papers and official HKEAA examiner reports.

อ่าน 3 นาทีอัปเดตเมื่อ: 21 มิ.ย. 2569

ภาพรวมข้อสอบ

จำนวนฉบับ

คะแนนเต็ม

153

เวลาสอบ

3ชม. 30นาที

ประเภทคำถาม

ฉบับ	เวลา	คะแนน	จำนวนข้อ	น้ำหนักคะแนน	ประเภทคำถาม
Paper 1 (Core Curriculum)	2ชม. 30นาที	117	45	60%	MCQ, Short Question, Long Question
Paper 2 (Elective Curriculum)	1ชม.	36	18	20%	MCQ, Structured Question

เกณฑ์เกรด

5**5*54321U

ข้อกำหนดเครื่องคิดเลข

Use only calculators on the HKEAA Approved List, bearing the 'H.K.E.A.A. APPROVED' (or older 'H.K.E.A. APPROVED') label. Programmable scientific models (e.g. Casio fx-50FH II, fx-3650P II) are allowed, and you MAY keep your own formulas/programs stored in memory — HKDSE does not require you to clear it. Graphic-display (graphing) and CAS/symbolic calculators are not on the approved list and must not be used.

AO1: Knowledge and Understanding (35%)
AO2: Evaluation and Translation (45%)
AO3: Experimental Skills and Investigation (20%)

จัดทำจากข้อสอบเก่าและเกณฑ์การให้คะแนนจริง (2021–2025)

โปรแกรมเครื่องคิดเลข

Resistors in Parallel

Casio fx-50FH II / fx-3650P II (HKEAA-approved programmable)

วัตถุประสงค์: Two resistors: \(R=\dfrac{R_1R_2}{R_1+R_2}\).

ใช้เมื่อใด: Combining two parallel resistors quickly.

ขั้นตอน

Prompt R1, R2; outputs the combined resistance.

โปรแกรม

?→A:?→B:AB÷(A+B)

ข้อควรระวังในการสอบ: For 3+ resistors apply it pairwise.

Thin Lens / Mirror Equation

Casio fx-50FH II / fx-3650P II (HKEAA-approved programmable)

วัตถุประสงค์: \(\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\Rightarrow f=\frac{uv}{u+v}\).

ใช้เมื่อใด: Lens/mirror problems given two of f, u, v.

ขั้นตอน

Prompt u, v; outputs f.

โปรแกรม

?→U:?→V:U V÷(U+V)

ข้อควรระวังในการสอบ: Keep the real-is-positive sign convention consistent.

Kinematics (v and s)

Casio fx-50FH II / fx-3650P II (HKEAA-approved programmable)

วัตถุประสงค์: Constant acceleration: \(v=u+at\), \(s=ut+\tfrac12at^2\).

ใช้เมื่อใด: Uniformly accelerated motion given u, a, t.

ขั้นตอน

Prompt u, a, t; outputs v then s.

โปรแกรม

?→U:?→A:?→T:U+A T◢U T+0.5A T²

ข้อควรระวังในการสอบ: Only valid for constant acceleration; use SI units.

ข้อผิดพลาดที่พบบ่อย

1highคะแนนที่เกี่ยวข้อง: 2Change of state: melting, boiling, latent heat
Arguing that using a copper cup is justified in heat transfer measurements because copper conducts heat faster.
วิธีหลีกเลี่ยง: State that copper is a good conductor of heat, which would significantly increase heat loss to the surroundings by conduction, making polystyrene (a good insulator) a much better choice to minimize errors.
2highคะแนนที่เกี่ยวข้อง: 2Force and Newton’s laws
Assuming the tension in the string is exactly equal to the weight of the hanging mass when the system is accelerating downwards.
วิธีหลีกเลี่ยง: Apply Newton's Second Law: because the hanging mass accelerates downwards, there must be a net downward force, meaning weight must be greater than tension (\( mg - T = ma \)). Therefore, tension \( T \) is smaller than weight.
3mediumคะแนนที่เกี่ยวข้อง: 2Gases: laws and kinetic theory
Assuming a gas cylinder can completely empty its gas contents into external containers/balloons.
วิธีหลีกเลี่ยง: Remember that once the pressure inside the cylinder drops to equal the ambient pressure (e.g., seabed pressure or atmospheric pressure), no more gas can flow out. The volume of gas remaining in the cylinder is still \( V \) at that ambient pressure.
4mediumคะแนนที่เกี่ยวข้อง: 2Electromagnetism & electromagnetic induction
Believing that eddy currents can only be induced in magnetic metals like iron, rather than any conductor.
วิธีหลีกเลี่ยง: Explain that eddy currents are induced in any metallic conductor (such as copper or aluminium sheets) experiencing a changing magnetic flux, in accordance with Faraday's Law and Lenz's Law.
5highคะแนนที่เกี่ยวข้อง: 2Gases: laws and kinetic theory
Using macroscopic arguments instead of kinetic theory to explain pressure changes in gases.
วิธีหลีกเลี่ยง: Always describe the microscopic behavior: state that pressure is due to molecules colliding with the walls, and link pressure changes to the average kinetic energy (speed) of molecules and their collision frequency per unit area.
6mediumคะแนนที่เกี่ยวข้อง: 1Uniform circular motion and gravitation
Omitting the negative sign in potential energy calculations when solving kinematics via conservation of energy.
วิธีหลีกเลี่ยง: For gravitational potential energy in orbits, use \( U = -\frac{GMm}{r} \) and carefully evaluate the difference: \( \Delta U = U_f - U_i \). Keep track of double negatives.

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