Physics IGCSE Summary

FORCES & MOTION

Average Speed:

  • (v)=st(v) = \frac{s}{t} (m/s for speed, m for distance, s for time)

Displacement-Time Graphs:

  • Straight line = constant speed

  • Curved line = changing speed (acceleration or deceleration)

Vector & Scalar Quantities:

  • Vector: has magnitude and direction (e.g., velocity, displacement)

  • Scalar: only has magnitude (e.g., speed, distance, time)

Acceleration:

  • Defined as rate of change of velocity

  • acceleration=v−ut\text{acceleration} = \frac{v - u}{t}

VELOCITY-TIME GRAPHS

  • Gradient: represents acceleration

  • Straight line: constant acceleration

  • Area under graph: displacement of object

FORCES

  • Forces:

    • Balanced forces = Resultant force = 0 (constant velocity)

    • Unbalanced forces = Resultant force > 0 (acceleration)

  • Weight: W=mgW = mg (gravitational field strength=g ≈ 9.81 m/s²

NEWTON'S LAWS

  • Newton's 2nd Law: F=maF = ma (force in Newtons, mass in kg, acceleration in m/s²)

  • Braking Distance: factors affecting include weight, surface conditions, etc.

AIR RESISTANCE & TERMINAL VELOCITY

  • Drag: force opposing the motion of an object through a fluid

  • Terminal Velocity: reached when drag force equals weight.

ELECTRICITY

  • Ring Main Circuit: includes live, neutral, and earth wires.

  • Fuses: protect circuits by melting under large current.

  • Power: P=VIP = VI (Power in Watts, Voltage in Volts, Current in Amperes)

CURRENT & VOLTAGE

  • Direct Current (DC): flows in one direction (e.g., batteries)

  • Alternating Current (AC): changes direction periodically (e.g., mains supply)

  • Voltage (V): energy per unit charge (Volts = Joules/Coulombs)

RESISTANCE

  • Resistance (R): energy used to move charges, expressed as V=IRV = IR

  • Types of Resistors:

    • Fixed, variable, thermistors, and light-dependent resistors (LDRs).

WAVES

  • Types of Waves:

    • Transverse Waves: vibration perpendicular to travel direction (e.g., light)

    • Longitudinal Waves: vibration parallel to travel direction (e.g., sound)

  • Reflection & Refraction: laws governing behavior at boundaries.

ELECTROMAGNETIC SPECTRUM

  • Categories: Radio, Microwave, Infrared, Visible Light, Ultraviolet, X-rays, Gamma rays.

  • Properties include wavelength, frequency, and speed.

TOTAL INTERNAL REFLECTION & OPTICAL FIBRES

  • Condition: occurs when light passes from dense to less dense medium.

  • Uses: in telecommunications and medical endoscopes.

SOUND WAVES

  • Produced by vibrations, travel via compressing and rarefying air particles.