OCR GCSE Physics Paper 1 Lecture Notes

Introduction

• Covers aspects of the first physics paper.
• Includes:
  • Matter
  • Forces
  • Electricity and Magnetism
• Applicable to: Foundation Tier, Double Combined, Triple (Separate Physics).
• Specific notes for Triple content will be highlighted.

Atomic Structure

• Development of Atomic Theory:

  • JJ Thompson: Discovered atoms consist of positive and negative charges (Plum Pudding Model).
  • Ernest Rutherford: Identified the nucleus as the small positive part of the atom.
  • Niels Bohr: Electrons exist in shells or orbitals.
  • James Chadwick: Discovered neutrons.

• Atomic Numbers and Isotopes:

  • Atomic number = number of protons.
  • Mass number = protons + neutrons.
  • Isotopes: Atoms of the same element with different numbers of neutrons.

Density

• Definition: Density = Mass/Volume
• Units: kg/m³
• Measurement:
  • Regular objects: Calculate using dimensions (e.g., cuboid: L x W x H).
  • Irregular objects: Use water displacement (Eureka can method).

States of Matter

• Solid, Liquid, Gas:

  • Solids: Particles vibrate in fixed positions.
  • Liquids: Particles are close but free to move.
  • Gases: Particles are far apart and move randomly.

• State Changes:

  • Melting/Evaporation requires energy to overcome forces between particles.

Specific Heat Capacity (SHC)

• Definition: SHC is the energy required to change temperature of 1 kg by 1°C.
• Equation: Energy = Mass x SHC x Change in Temperature
• Practical Considerations: Energy loss to surroundings affects accuracy.

Internal Energy

• Definition: Sum of kinetic and potential energy of particles.
• Changes During State Changes:
  • No change in temperature during state change but potential energy changes.

Pressure and Gases

• Basics:

  • Pressure: Force per unit area (P = F/A), measured in pascals (Pa).
  • Gas laws: Pressure x Volume = constant (at constant temperature).

• Pressure in Fluids:

  • Increases with depth due to weight of water above.
  • Equation: Pressure = Height x Density x Gravitational field strength.

Forces

• Types:

  • Contact forces: Friction, tension.
  • Non-contact forces: Gravity, electrostatic, magnetic.

• Newton's Laws:

  • First Law: An object in motion stays in motion unless acted upon.
  • Second Law: F = ma (force equals mass times acceleration).
  • Third Law: For every action, there is an equal and opposite reaction.

Momentum

• Definition: Momentum = Mass x Velocity (a vector quantity).
• Conservation: Total momentum before and after a collision is conserved.

Electricity

• Basic Concepts:

  • Current: Flow of electric charge (measured in amps).
  • PD/Voltage: Energy per charge (measured in volts).
  • Resistance: Opposition to current (Ohm's Law: V = IR).

• Circuit Elements:

  • Series circuits: Total PD is shared, current is same.
  • Parallel circuits: PD is same, total current is shared.

Magnetism and Electromagnetism

• Magnet Basics:

  • Permanent magnets: Have constant magnetic field.
  • Induced magnetism: Temporary magnetism when in a field.

• Motor Effect:

  • Moving wire in magnetic field experiences a force.
  • Equation: F = BIL (Force = Magnetic flux density x Current x Length).

Generators and Transformers

• Generator Effect: Movement induces current or PD.
• Transformers:
  • Step-up: Increases voltage for transmission.
  • Step-down: Decreases voltage for safe use.
  • Based on electromagnetic induction, requiring AC.

Final Notes

• Practice calculations and understand the theory behind each principle.
• Use units consistently and understand vector vs scalar quantities.