Cambridge IGCSE Physics (0625 & 0972) Master Revision Guide: Comprehensive breakdown of mechanics, thermal physics, waves, electricity, magnetism, and nuclear physics by Dr. Khaled Dabour (DABOURHUB Academy).
1. Motion, Forces & Energy: Core Mathematical Foundations
Understanding kinematic graphs and applying Newton’s laws are central to securing high marks in Physics:
- Speed vs. Velocity: Speed is a scalar quantity (magnitude only), whereas velocity is a vector quantity (magnitude and direction). Acceleration is the rate of change of velocity: a = (v – u) ÷ t.
- Interpreting Velocity-Time Graphs:
- Gradient (Slope): Represents the acceleration of the object. A horizontal flat line indicates constant velocity (zero acceleration).
- Area under the graph: Represents the total distance travelled (calculated by dividing the shape into triangles and rectangles).
- Newton’s Second Law: Resultant Force (F) = mass (m) × acceleration (a). Unit: Newtons (N).
- Terminal Velocity: When an object falls through air, air resistance increases with speed until it equals weight (downward gravitational force). Resultant force becomes zero, acceleration ceases, and constant terminal velocity is attained.
2. Thermal Physics & Heat Transfer Mechanisms
Thermal energy transfers via three main mechanisms: conduction (in solids via atomic vibrations and free electron diffusion in metals), convection (in fluids via density changes creating convection currents), and radiation (electromagnetic infra-red waves requiring no medium).
Specific Heat Capacity Formula: ΔE = m × c × Δθ
Where ΔE = thermal energy transferred (Joules), m = mass (kg), c = specific heat capacity (J/(kg·°C)), and Δθ = temperature change (°C).
3. Electricity, Magnetism & Circuit Laws
Electrical circuits obey Ohm’s Law and conservation of charge and energy:
| Circuit Parameter | Series Circuit | Parallel Circuit |
|---|---|---|
| Current (I) | Current is the same at every point (I = I₁ = I₂) | Total current divides between branches (I_total = I₁ + I₂) |
| Voltage (V) | Total voltage splits across components (V_total = V₁ + V₂) | Voltage across each parallel branch is equal to source voltage |
| Total Resistance (R) | R_total = R₁ + R₂ | 1/R_total = 1/R₁ + 1/R₂ (Total resistance is less than smallest branch) |
4. Exam Technique & Avoiding Common Pitfalls
- Always write the general formula first before substituting numbers to secure method marks even if a calculation slip occurs.
- State the correct SI unit for every numerical final answer (e.g. J, W, N, m/s², Ω).
- Give final answers to 2 or 3 significant figures matching the precision of given data in the question prompt.