Source: https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-9-gravity

[Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [IGCSE](https://senecalearning.com/en-gb/revision-notes/igcse.md) › [Physics](https://senecalearning.com/en-gb/revision-notes/igcse/physics.md) › [Cambridge International](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international.md) › [Higher](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher.md) › Gravity

# Gravity

Physics: Cambridge International GCSE Supplement, topic 1.2.9

## Free Fall

If an object is in free fall, then the object’s weight is the only force acting on it. The weight of an object is the force that acts downwards on an object due to gravity.

### Free fall

![Free fall](https://image-v2.cdn.app.senecalearning.com/2025-08/6f169302-99e2-4623-a3e4-0c901925fc94/8d22a2c8-de22-43fd-89e0-97866448e9e7.png)

- The acceleration caused by gravity is constant, as long as air resistance is ignored.
- This constant acceleration is called free fall.
- Air resistance can reduce the acceleration. 
 - But the force of gravity itself stays the same.

### Acceleration due to gravity

![Acceleration due to gravity](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/1.2.2%20Gravity%20and%20free-fall/diving-1600668_640-min%20-%20Edited.jpg)

- An object in free fall will accelerate at a constant rate. 
- This constant rate is called the acceleration due to gravity (g). 
- The average value for acceleration on Earth due to gravity is 9.8 m/s2.

## Test yourself on Gravity

- What is the definition of weight?
- Which of the following are true?
- An object falling from a plane towards the ground...

[Practise this topic for free](https://app.senecalearning.com/classroom/course/800680e0-d9b4-11e7-8664-d19507716171/section/e0ed78d0-d9ca-11e7-a634-fb4be20e55cc/session)

- Previous topic: [1.2.8 Calculating Uniform Acceleration](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-8-calculating-uniform-acceleration.md)
- Next topic: [1.2.10 Free Fall - Distance-Time & Speed-Time Graphs](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-10-free-fall-distance-time-and-speed-time-graphs.md)

## Physics: Cambridge International GCSE Supplement contents

### 1 Motion, Forces & Energy
- 1.1 Physical Quantities & Measurement Techniques
  - [1.1.1 Measuring Length](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-1-1-measuring-length.md)
  - [1.1.2 Measuring Volume](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-1-2-measuring-volume.md)
  - [1.1.3 Measuring Time](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-1-3-measuring-time.md)
  - [1.1.4 Scalar & Vector Quantities](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-1-4-scalar-and-vector-quantities.md)
  - [1.1.5 Adding Vectors](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-1-5-adding-vectors.md)
- 1.2 Motion
  - [1.2.1 Average Speed](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-1-average-speed.md)
  - [1.2.2 Calculating Average Speed](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-2-calculating-average-speed.md)
  - [1.2.3 Velocity](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-3-velocity.md)
  - [1.2.4 Acceleration](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-4-acceleration.md)
  - [1.2.5 Distance-Time Graphs](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-5-distance-time-graphs.md)
  - [1.2.6 Speed-Time Graphs](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-6-speed-time-graphs.md)
  - [1.2.7 More Speed-Time Graphs](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-7-more-speed-time-graphs.md)
  - [1.2.8 Calculating Uniform Acceleration](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-8-calculating-uniform-acceleration.md)
  - [1.2.9 Gravity](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-9-gravity.md)
  - [1.2.10 Free Fall - Distance-Time & Speed-Time Graphs](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-10-free-fall-distance-time-and-speed-time-graphs.md)
  - [1.2.11 Air Resistance](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-11-air-resistance.md)
  - [1.2.12 Air Resistance - Graphs](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-12-air-resistance-graphs.md)
  - [1.2.13 Optional: Calculating Acceleration](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-2-13-optional-calculating-acceleration.md)
- 1.3 Mass & Weight
  - [1.3.1 Mass](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-3-1-mass.md)
  - [1.3.2 Weight](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-3-2-weight.md)
  - [1.3.3 Gravity Calculations](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-3-3-gravity-calculations.md)
- 1.4 Density
  - [1.4.1 Density](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-4-1-density.md)
  - [1.4.2 Equation for Density](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-4-2-equation-for-density.md)
  - [1.4.3 Density - Experiments](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-4-3-density-experiments.md)
  - [1.4.4 Density - Calculations](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-4-4-density-calculations.md)
- 1.5 Forces: Effects of Forces
  - [1.5.1 Spring Constant](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-5-1-spring-constant.md)
  - [1.5.2 Spring Constant Equation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-5-2-spring-constant-equation.md)
  - [1.5.3 Force & Acceleration](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-5-3-force-and-acceleration.md)
  - [1.5.4 Friction](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-5-4-friction.md)
- 1.6 Forces: Turning Effects of Forces
  - [1.6.1 Circular Motion](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-6-1-circular-motion.md)
  - [1.6.2 Turning Effect](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-6-2-turning-effect.md)
  - [1.6.3 Moments](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-6-3-moments.md)
  - [1.6.4 Calculating Moments](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-6-4-calculating-moments.md)
- 1.7 Forces: Centre of Gravity
  - [1.7.1 Equilibrium](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-7-1-equilibrium.md)
  - [1.7.2 Centre of Gravity](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-7-2-centre-of-gravity.md)
  - [1.7.3 Centre of Gravity Experiment](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-7-3-centre-of-gravity-experiment.md)
- 1.8 Momentum
  - [1.8.1 Momentum](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-8-1-momentum.md)
- 1.9 Energy, Work, & Power: Energy
  - [1.9.1 Energy Changes](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-9-1-energy-changes.md)
  - [1.9.2 Energy Conversion](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-9-2-energy-conversion.md)
  - [1.9.3 Kinetic Energy Stored](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-9-3-kinetic-energy-stored.md)
  - [1.9.4 Calculating Changes in Kinetic Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-9-4-calculating-changes-in-kinetic-energy.md)
  - [1.9.5 Gravitational Potential Energy Stored](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-9-5-gravitational-potential-energy-stored.md)
  - [1.9.6 Calculating Changes in GPE](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-9-6-calculating-changes-in-gpe.md)
  - [1.9.7 Elastic Potential Energy Stored](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-9-7-elastic-potential-energy-stored.md)
  - [1.9.8 Calculating Changes in EPE](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-9-8-calculating-changes-in-epe.md)
- 1.10 Energy, Work & Power: Work
  - [1.10.1 Mechanical Work](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-10-1-mechanical-work.md)
  - [1.10.2 Calculating Mechanical Work](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-10-2-calculating-mechanical-work.md)
  - [1.10.3 Calculating Electrical Work Done](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-10-3-calculating-electrical-work-done.md)
- 1.11 Energy, Work & Power: Energy Resources
  - [1.11.1 Energy Resources](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-1-energy-resources.md)
  - [1.11.2 Fossil Fuels](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-2-fossil-fuels.md)
  - [1.11.3 Geothermal Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-3-geothermal-energy.md)
  - [1.11.4 Wind Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-4-wind-energy.md)
  - [1.11.5 Water Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-5-water-energy.md)
  - [1.11.6 Tidal Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-6-tidal-energy.md)
  - [1.11.7 Nuclear Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-7-nuclear-energy.md)
  - [1.11.8 Solar Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-8-solar-energy.md)
  - [1.11.9 Original Source of Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-9-original-source-of-energy.md)
  - [1.11.10 Fusion](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-10-fusion.md)
  - [1.11.11 Efficiency](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-11-efficiency.md)
  - [1.11.12 Calculating Efficiency](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-12-calculating-efficiency.md)
  - [1.11.13 Energy Wastage](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-11-13-energy-wastage.md)
- 1.12 Energy, Work & Power: Power
  - [1.12.1 Power](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-12-1-power.md)
- 1.13 Pressure
  - [1.13.1 Pressure](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-13-1-pressure.md)
  - [1.13.2 Atmospheric Pressure](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-13-2-atmospheric-pressure.md)
  - [1.13.3 Calculating Pressure](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-13-3-calculating-pressure.md)
  - [1.13.4 Liquid Pressure](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-13-4-liquid-pressure.md)
  - [1.13.5 Manometer](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-13-5-manometer.md)
  - [1.13.6 Calculating Liquid Pressure](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/1-13-6-calculating-liquid-pressure.md)

### 2 Thermal Physics
- 2.1 Kinetic Particle Model of Matter
  - [2.1.1 Kinetic Particle Model of Matter](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-1-1-kinetic-particle-model-of-matter.md)
  - [2.1.2 States of Matter](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-1-2-states-of-matter.md)
  - [2.1.3 Properties of Gases](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-1-3-properties-of-gases.md)
- 2.2 Thermal Properties & Temperature
  - [2.2.1 Thermal Expansion](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-1-thermal-expansion.md)
  - [2.2.2 Changes in Internal Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-2-changes-in-internal-energy.md)
  - [2.2.3 Heat Capacities](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-3-heat-capacities.md)
  - [2.2.4 Heat Capacities Experiment](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-4-heat-capacities-experiment.md)
  - [2.2.5 Internal Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-5-internal-energy.md)
  - [2.2.6 Calculating Internal Energy](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-6-calculating-internal-energy.md)
  - [2.2.7 End of Topic Test - Thermal Physics](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-7-end-of-topic-test-thermal-physics.md)
  - [2.2.8 Changes of State](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-8-changes-of-state.md)
  - [2.2.9 Evaporation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-9-evaporation.md)
  - [2.2.10 Factors Affecting Evaporation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-10-factors-affecting-evaporation.md)
  - [2.2.11 Examples of Evaporation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-2-11-examples-of-evaporation.md)
- 2.3 Transfer of Thermal Energy
  - [2.3.1 Conduction](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-3-1-conduction.md)
  - [2.3.2 Molecular Conduction](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-3-2-molecular-conduction.md)
  - [2.3.3 Convection Currents](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-3-3-convection-currents.md)
  - [2.3.4 Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-3-4-radiation.md)
  - [2.3.5 Surface Colour](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-3-5-surface-colour.md)
  - [2.3.6 Emitting Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-3-6-emitting-radiation.md)
  - [2.3.7 Leslie's Cube & Other Radiation Experiments](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-3-7-leslies-cube-and-other-radiation-experiments.md)
  - [2.3.8 Uses of Energy Transfer](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/2-3-8-uses-of-energy-transfer.md)

### 3 Waves
- 3.1 General Properties of Waves
  - [3.1.1 Wave Basics](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-1-wave-basics.md)
  - [3.1.2 Transverse Wave](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-2-transverse-wave.md)
  - [3.1.3 Longitudinal Wave](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-3-longitudinal-wave.md)
  - [3.1.4 Ripple Tank](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-4-ripple-tank.md)
  - [3.1.5 Wave Speed](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-5-wave-speed.md)
  - [3.1.6 Wave Speed Formula](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-6-wave-speed-formula.md)
  - [3.1.7 Calculating Wave Speed](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-7-calculating-wave-speed.md)
  - [3.1.8 Wave Frequency](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-8-wave-frequency.md)
  - [3.1.9 Calculating Wave Frequency](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-9-calculating-wave-frequency.md)
  - [3.1.10 Wavelength](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-10-wavelength.md)
  - [3.1.11 Diffraction](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-1-11-diffraction.md)
- 3.2 Light: Reflection & Refraction
  - [3.2.1 Reflection](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-1-reflection.md)
  - [3.2.2 Internal Reflection](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-2-internal-reflection.md)
  - [3.2.3 Refraction](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-3-refraction.md)
  - [3.2.4 More Refraction](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-4-more-refraction.md)
  - [3.2.5 Refractive Index Equation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-5-refractive-index-equation.md)
  - [3.2.6 Refractive Index](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-6-refractive-index.md)
  - [3.2.7 Critical Angle](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-7-critical-angle.md)
  - [3.2.8 Optical Fibres](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-8-optical-fibres.md)
  - [3.2.9 Optical Fibres in Communications](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-9-optical-fibres-in-communications.md)
  - [3.2.10 Medical Applications of Optical Fibres](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-2-10-medical-applications-of-optical-fibres.md)
- 3.3 Light: Thin Lenses
  - [3.3.1 Thin Converging Lenses 1](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-3-1-thin-converging-lenses-1.md)
  - [3.3.2 Thin Converging Lens 2](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-3-2-thin-converging-lens-2.md)
  - [3.3.3 Thin Converging Lens 3](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-3-3-thin-converging-lens-3.md)
  - [3.3.4 Thin Converging Lens 4](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-3-4-thin-converging-lens-4.md)
  - [3.3.5 Calculating Lenses](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-3-5-calculating-lenses.md)
- 3.4 Light: Dispersion of Light
  - [3.4.1 Dispersion of Light](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-4-1-dispersion-of-light.md)
  - [3.4.2 Triangular Prisms 1](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-4-2-triangular-prisms-1.md)
  - [3.4.3 Triangular Prisms 2](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-4-3-triangular-prisms-2.md)
- 3.5 Electromagnetic Spectrum
  - [3.5.1 Properties of Electromagnetic Waves](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-1-properties-of-electromagnetic-waves.md)
  - [3.5.2 Gamma Rays](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-2-gamma-rays.md)
  - [3.5.3 X-Rays](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-3-x-rays.md)
  - [3.5.4 UV Light](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-4-uv-light.md)
  - [3.5.5 Visible Light](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-5-visible-light.md)
  - [3.5.6 Infrared Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-6-infrared-radiation.md)
  - [3.5.7 Microwaves](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-7-microwaves.md)
  - [3.5.8 Radio Waves](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-8-radio-waves.md)
  - [3.5.9 Other Uses of EM Waves](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-9-other-uses-of-em-waves.md)
  - [3.5.10 Analogue & Digital Signals](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-5-10-analogue-and-digital-signals.md)
- 3.6 Sound
  - [3.6.1 Sound Waves](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-6-1-sound-waves.md)
  - [3.6.2 Ears](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-6-2-ears.md)
  - [3.6.3 Speed of Sound](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-6-3-speed-of-sound.md)
  - [3.6.4 Measuring Sound Waves](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-6-4-measuring-sound-waves.md)
  - [3.6.5 Oscilloscope Traces](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-6-5-oscilloscope-traces.md)
  - [3.6.6 Sound Waves Experiment](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/3-6-6-sound-waves-experiment.md)

### 4 Electricity & Magnetism
- 4.1 Simple Phenomena of Magnetism
  - [4.1.1 Magnets](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-1-1-magnets.md)
  - [4.1.2 Magnetic Forces](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-1-2-magnetic-forces.md)
  - [4.1.3 Magnetic Materials](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-1-3-magnetic-materials.md)
  - [4.1.4 Induced Magnetism](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-1-4-induced-magnetism.md)
  - [4.1.5 Temporary & Permanent Magnets](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-1-5-temporary-and-permanent-magnets.md)
  - [4.1.6 Electromagnets](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-1-6-electromagnets.md)
  - [4.1.7 Magnetic Field Lines](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-1-7-magnetic-field-lines.md)
- 4.2 Electrical Quantities: Electric Charge
  - [4.2.1 Electrical Charge](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-2-1-electrical-charge.md)
  - [4.2.2 Charged Objects](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-2-2-charged-objects.md)
  - [4.2.3 Static Electricity Experiments](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-2-3-static-electricity-experiments.md)
  - [4.2.4 Charging by Induction](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-2-4-charging-by-induction.md)
  - [4.2.5 Electric Fields](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-2-5-electric-fields.md)
  - [4.2.6 Electric Field Patterns](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-2-6-electric-field-patterns.md)
  - [4.2.7 Conductors](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-2-7-conductors.md)
  - [4.2.8 Electrical Conductors - Electrons](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-2-8-electrical-conductors-electrons.md)
- 4.3 Electrical Quantities: Electric Current
  - [4.3.1 Current](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-3-1-current.md)
  - [4.3.2 Conventional Current](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-3-2-conventional-current.md)
  - [4.3.3 Current Equation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-3-3-current-equation.md)
  - [4.3.4 Calculating Current](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-3-4-calculating-current.md)
  - [4.3.5 AC/DC](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-3-5-acdc.md)
- 4.4 Electromotive Force & Potential Difference
  - [4.4.1 Electromotive Force](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-4-1-electromotive-force.md)
  - [4.4.2 Potential Difference](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-4-2-potential-difference.md)
  - [4.4.3 Potential Difference Equation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-4-3-potential-difference-equation.md)
  - [4.4.4 Calculating Voltage](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-4-4-calculating-voltage.md)
- 4.5 Electrical Quantities: Resistance
  - [4.5.1 Circuit Measurements](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-5-1-circuit-measurements.md)
  - [4.5.2 Resistance](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-5-2-resistance.md)
  - [4.5.3 Equation for Resistance](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-5-3-equation-for-resistance.md)
  - [4.5.4 Measuring Resistance](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-5-4-measuring-resistance.md)
  - [4.5.5 Calculating Resistance & Ohm's Law](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-5-5-calculating-resistance-and-ohms-law.md)
  - [4.5.6 Variable Resistance](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-5-6-variable-resistance.md)
  - [4.5.7 Resistance Graph](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-5-7-resistance-graph.md)
- 4.6 Electrical Energy & Electrical Power
  - [4.6.1 Electrical Work](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-6-1-electrical-work.md)
  - [4.6.2 Electrical Power](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-6-2-electrical-power.md)
  - [4.6.3 Calculating Electrical Work](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-6-3-calculating-electrical-work.md)
- 4.7 Electric Circuits: Circuit Diagrams & Components
  - [4.7.1 Circuit Diagrams](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-7-1-circuit-diagrams.md)
  - [4.7.2 Circuit Symbols](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-7-2-circuit-symbols.md)
  - [4.7.3 More Circuit Symbols](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-7-3-more-circuit-symbols.md)
  - [4.7.4 Diodes](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-7-4-diodes.md)
  - [4.7.5 LDRs & Thermistors](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-7-5-ldrs-and-thermistors.md)
- 4.8 Electric Circuits: Series & Parallel Circuits
  - [4.8.1 Series Circuits](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-1-series-circuits.md)
  - [4.8.2 Series Circuits - Resistors](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-2-series-circuits-resistors.md)
  - [4.8.3 Series Circuits - Cells](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-3-series-circuits-cells.md)
  - [4.8.4 Series Circuits - Potential Difference](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-4-series-circuits-potential-difference.md)
  - [4.8.5 Calculating Series Circuits](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-5-calculating-series-circuits.md)
  - [4.8.6 Parallel Circuits](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-6-parallel-circuits.md)
  - [4.8.7 Parallel Circuits - Current](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-7-parallel-circuits-current.md)
  - [4.8.8 Parallel Circuits - Resistance](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-8-parallel-circuits-resistance.md)
  - [4.8.9 Parallel Circuits in Practice](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-8-9-parallel-circuits-in-practice.md)
- 4.9 Electric Circuits: Action & Use
  - [4.9.1 Potentiometer](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-9-1-potentiometer.md)
  - [4.9.2 Potential Divider Equation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-9-2-potential-divider-equation.md)
- 4.10 Electrical Safety
  - [4.10.1 Dangers of Electricity](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-10-1-dangers-of-electricity.md)
  - [4.10.2 Live & Neutral Wires](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-10-2-live-and-neutral-wires.md)
  - [4.10.3 Earthing Metal Cases](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-10-3-earthing-metal-cases.md)
  - [4.10.4 Fuses & Trip Switches](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-10-4-fuses-and-trip-switches.md)
  - [4.10.5 Fuse Ratings](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-10-5-fuse-ratings.md)
- 4.11 Electromagnetic Effects: Electromagnetic Induction
  - [4.11.1 Electromagnetic Induction](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-11-1-electromagnetic-induction.md)
  - [4.11.2 Size of e.m.f](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-11-2-size-of-emf.md)
  - [4.11.3 Forces Between Electricity & Magnets](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-11-3-forces-between-electricity-and-magnets.md)
  - [4.11.4 Rotation of Coil & Induced e.m.f](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-11-4-rotation-of-coil-and-induced-emf.md)
- 4.12 Electromagnetic Effects: The A.C. Generator
  - [4.12.1 The Rotating-Coil Generator](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-12-1-the-rotating-coil-generator.md)
  - [4.12.2 Features of a Rotating-Coil Generator](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-12-2-features-of-a-rotating-coil-generator.md)
- 4.13 Magnetic Effect of a Current
  - [4.13.1 Magnetic Effect of a Current](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-13-1-magnetic-effect-of-a-current.md)
  - [4.13.2 Solenoid Field](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-13-2-solenoid-field.md)
  - [4.13.3 Relays](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-13-3-relays.md)
- 4.14 Force on a Current-Carrying Conductor
  - [4.14.1 Magnetic Field Strength](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-14-1-magnetic-field-strength.md)
  - [4.14.2 Uses of Magnets & Currents](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-14-2-uses-of-magnets-and-currents.md)
  - [4.14.3 Catapult Experiment](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-14-3-catapult-experiment.md)
  - [4.14.4 Beam Force Experiment](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-14-4-beam-force-experiment.md)
- 4.15 Electromagnetic Effects: The D.C. Motor
  - [4.15.1 Motor Effect](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-15-1-motor-effect.md)
  - [4.15.2 Direction of Motor Effect](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-15-2-direction-of-motor-effect.md)
  - [4.15.3 DC Motors](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-15-3-dc-motors.md)
  - [4.15.4 Coil of Wire in a Magnetic Field](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-15-4-coil-of-wire-in-a-magnetic-field.md)
- 4.16 Electromagnetic Effects: The Transformer
  - [4.16.1 Transformers](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-16-1-transformers.md)
  - [4.16.2 Transformers Equation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-16-2-transformers-equation.md)
  - [4.16.3 Types of Transformer](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-16-3-types-of-transformer.md)
  - [4.16.4 Principles of Transformer Operation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-16-4-principles-of-transformer-operation.md)
  - [4.16.5 Energy in Transformers](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/4-16-5-energy-in-transformers.md)

### 5 Nuclear Physics
- 5.1 The Nuclear Model of the Atom
  - [5.1.1 Atomic Model](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-1-atomic-model.md)
  - [5.1.2 Scattering of Alpha Particles](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-2-scattering-of-alpha-particles.md)
  - [5.1.3 Subatomic Particles](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-3-subatomic-particles.md)
  - [5.1.4 Proton & Nucleon Numbers](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-4-proton-and-nucleon-numbers.md)
  - [5.1.5 Calculating Number of Neutrons](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-5-calculating-number-of-neutrons.md)
  - [5.1.6 Isotopes](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-6-isotopes.md)
  - [5.1.7 More Isotopes](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-7-more-isotopes.md)
  - [5.1.8 Carbon Nuclides](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-8-carbon-nuclides.md)
  - [5.1.9 Nuclear Fusion](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-9-nuclear-fusion.md)
  - [5.1.10 Nuclear Fission](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-10-nuclear-fission.md)
  - [5.1.11 More Nuclear Fission](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-1-11-more-nuclear-fission.md)
- 5.2 Radioactivity: Detection of Radioactivity
  - [5.2.1 Radioactivity](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-2-1-radioactivity.md)
  - [5.2.2 Types of Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-2-2-types-of-radiation.md)
  - [5.2.3 Detection of Radioactivity](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-2-3-detection-of-radioactivity.md)
  - [5.2.4 Background Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-2-4-background-radiation.md)
- 5.3 Radioactivity: The Three Types of Nuclear Emission
  - [5.3.1 Three Types of Emission](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-3-1-three-types-of-emission.md)
  - [5.3.2 Relative Ionising Effects](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-3-2-relative-ionising-effects.md)
  - [5.3.3 Electric Fields](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-3-3-electric-fields.md)
  - [5.3.4 Magnetic Fields Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-3-4-magnetic-fields-radiation.md)
- 5.4 Radioactive Decay
  - [5.4.1 Radioactive Decay](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-4-1-radioactive-decay.md)
  - [5.4.2 Decay Equations](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-4-2-decay-equations.md)
  - [5.4.3 Half Life](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-4-3-half-life.md)
  - [5.4.4 Measuring Half-Life](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-4-4-measuring-half-life.md)
  - [5.4.5 Practical Applications of Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-4-5-practical-applications-of-radiation.md)
  - [5.4.6 Ionising Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-4-6-ionising-radiation.md)
  - [5.4.7 Safety Precautions](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/5-4-7-safety-precautions.md)

### 6 Space Physics
- 6.1 The Earth & the Solar System
  - [6.1.1 The Earth](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-1-1-the-earth.md)
  - [6.1.2 The Moon](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-1-2-the-moon.md)
  - [6.1.3 The Solar System & The Accretion Model](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-1-3-the-solar-system-and-the-accretion-model.md)
  - [6.1.4 Gravitational Field & Speed of Light](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-1-4-gravitational-field-and-speed-of-light.md)
  - [6.1.5 The Sun's Gravitational Field](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-1-5-the-suns-gravitational-field.md)
- 6.2 Stars & the Universe
  - [6.2.1 The Sun as a Star](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-1-the-sun-as-a-star.md)
  - [6.2.2 Galaxies](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-2-galaxies.md)
  - [6.2.3 Life Cycle of a Star like the Sun](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-3-life-cycle-of-a-star-like-the-sun.md)
  - [6.2.4 Life Cycle of a Star Much Bigger than the Sun](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-4-life-cycle-of-a-star-much-bigger-than-the-sun.md)
  - [6.2.5 Creation of Elements](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-5-creation-of-elements.md)
  - [6.2.6 Red-shift](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-6-red-shift.md)
  - [6.2.7 The Big Bang](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-7-the-big-bang.md)
  - [6.2.8 Cosmic Microwave Background Radiation](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-8-cosmic-microwave-background-radiation.md)
  - [6.2.9 The Hubble Constant](https://senecalearning.com/en-gb/revision-notes/igcse/physics/cambridge-international/higher/6-2-9-the-hubble-constant.md)
