IGCSE Physics (9-1) Revision Notes

Section 1: Forces and Motion

Units

• Mass: Kilogram (kg)
• Distance: Metre (m)
• Speed/Velocity: Metre per second (m/s)
• Acceleration: Metre per second squared (m/s²)
• Force: Newton (N)
• Time: Second (s)
• Gravitational acceleration: Newton per kilogram (N/kg)
• Momentum: Kilogram metre per second (kg m/s)

Movement and Position

• Distance: Change in position of an object.
• Displacement: Change in position in a particular direction.
• Distance-Time Graphs: Represents speed or velocity; slope = speed.
• Velocity-Time Graphs: Show acceleration; area under graph = distance travelled.
• Speed: Rate of change of distance; average speed = total distance/total time.
• Velocity: Speed in a specific direction.

Forces, Movement, Shape, and Momentum

• Effects of Forces: Change in speed, shape, or direction.
• Types of Forces: Gravitational, normal reaction, air resistance, upthrust, magnetic, electrostatic, tension, frictional.
• Friction: Opposes motion; types include kinetic, static, rolling, fluid.
• Newton's Laws: 3rd Law - For every action, there is an equal and opposite reaction.
• Momentum: Product of mass and velocity; conserved in collisions.

Experiments

• Measuring Speed: Using stopwatches, light gates, ticker tapes.
• Measuring Acceleration: Using video sequences, modern Galileo experiments.
• Investigating Friction: Effects of mass, surface roughness.
• Investigating Forces: Using pulleys and trolleys to study F ∝ a.

Section 2: Electricity

Units

• Current: Ampere (A)
• Charge: Coulomb (C)
• Energy: Joule (J)
• Resistance: Ohm (Ω)
• Voltage: Volt (V)
• Power: Watt (W)

Mains Electricity

• Hazards: Frayed cables, water around sockets, metal objects in sockets.
• Safety Devices: Fuses, circuit breakers, insulation, earthing.
• Current in Resistors: Converts electrical energy to heat.
• AC vs DC: AC changes direction; DC flows in one direction.

Circuits

• Series Circuits: Shared voltage, if one component fails, all fail.
• Parallel Circuits: Same voltage across branches; components can be controlled independently.
• Ohm’s Law: V = IR; describes voltage, current, resistance relationship.

Experiments

• Investigating Ohm’s Law: Measuring current and voltage across resistors.
• Effect of Resistance: Higher resistance means lower current.

Section 3: Waves

Units

• Frequency: Hertz (Hz)
• Wavelength: Metre (m)
• Wave speed: Metre per second (m/s)

Properties of Waves

• Transverse vs Longitudinal: Transverse - vibrations perpendicular; Longitudinal - vibrations parallel.
• Energy Transfer: Waves transfer energy but not matter.
• Wave Equation: v = fλ (speed = frequency × wavelength)

Electromagnetic Spectrum

• Continuous Spectrum: Includes radio waves to gamma rays; light is visible spectrum.
• Uses: Radio - communication; Microwaves - cooking, communication; Infrared - heating, night vision.
• Dangers: UV - skin cancer; X-rays - cancer risk; Gamma - cell damage.

Light and Sound

• Reflection and Refraction: Light changes direction on passing through different media.
• Sound Waves: Longitudinal; can be reflected, refracted, diffracted.

Section 4: Energy Resources and Energy Transfer

Units

• Energy: Joule (J)
• Power: Watt (W)

Energy Transfer

• Forms of Energy: Thermal, light, electrical, sound, kinetic, chemical, nuclear, potential.
• Conservation of Energy: Energy is not created or destroyed, only transformed.
• Efficiency: Ratio of useful energy output to total energy input.

Work and Power

• Work: Force x Distance; measured in joules.
• Power: Rate of energy transfer; Power = Work/Time.

Energy Resources

• Renewable: Solar, wind, hydroelectric, geothermal; clean but variable.
• Non-renewable: Fossil fuels, nuclear; reliable but polluting.

Section 5: Solids, Liquids, and Gases

Units

• Pressure: Pascal (Pa)
• Density: Kilogram per cubic metre (kg/m³)

Density and Pressure

• Density: Mass/Volume.
• Pressure: Force/Area; acts in all directions in fluids.

Change of State

• Melting, Boiling, Evaporation: Heat increases particle movement; change state.
• Particle Arrangements: Solids - fixed; Liquids - flow; Gases - spread out.

Section 6: Magnetism and Electromagnetism

Magnetism

• Magnetic Fields: Produced by magnets and electric currents.
• Electromagnets: Temporary magnets created with electric current.

Electromagnetism

• Current in Magnetic Field: Experiences a force; basis of motors and speakers.
• Induced Voltage: Voltage induced by changing magnetic field; basis of generators.

Section 7: Radioactivity and Particles

Radioactivity

• Radiation Types: Alpha, beta, gamma.
• Radioactive Decay: Random process, measured in Becquerels.
• Half-Life: Time for activity to reduce to half.

Uses of Radioactivity

• Medical: Tracers, radiotherapy.
• Industrial: Tracing leaks, thickness gauges.
• Dating: Carbon dating for age estimation.

Section 8: Astrophysics

Stellar Evolution

• Star Lifecycle: From nebula to black hole or dwarf star.
• Galaxies and Universe: Galactic structures, universe expansion.

Cosmology

• Big Bang Theory: Universe origin theory; supported by redshift observations.