Edexcel GCSE Physics Paper 2: Key Topics and Concepts

General Information

• Suitable for Double Combined and Triple/Separate Science (High and Foundation tier)
• Covers Topics: Energy, Forces, Electricity, Magnetism, and Particles

Energy

• Concept: Energy is conserved; it cannot be created or destroyed (except for mass-energy equivalence in nuclear processes).
• Key Energy Stores:
  • Kinetic Energy (E): E = 1/2 mv^2 (mass in kg, speed in m/s)
  • Gravitational Potential Energy (GPE): E = mgh (mass in kg, gravitational field strength in N/kg, height in meters)
  • Elastic Potential Energy: E = 1/2 ke^2 (spring constant in N/m, extension in meters)
  • Thermal Energy (Change in Thermal Energy): ΔE = mcΔT (mass in kg, specific heat capacity in J/kg°C, temperature change in °C)
  • Chemical Potential Energy: Found in food and fuels.
• Energy Transfer: In a closed system, the total energy is constant. For example, GPE lost equals kinetic energy gained.
• Specific Heat Capacity Practical: Measuring temperature change to find specific heat capacity.
• Power: P = E/t (Power in watts, Energy in joules, Time in seconds).
• Efficiency: Useful energy output divided by total energy input.

Forces

• Types: Contact (friction, air resistance) and Non-contact (magnetism, gravity).
• Vectors: Represented by arrows showing magnitude and direction.
• Resultant Force: Sum of all forces acting on an object.
• Newton's First Law: An object will remain at rest or move at a constant velocity if forces are balanced.
• Hooke's Law: F = ke (Force in N, spring constant in N/m, extension in m).
• Work Done: W = Fs (force in N, distance in m); equivalent to energy transferred.
• Moments: Moment = F * distance from pivot.
• Pressure: P = F/A (force in N, area in m²).

Electricity

• Circuits: Flow of charge (electrons) through a complete loop.
  • Components: Battery, resistors, voltmeters, etc.
  • Equations:
    • Potential Difference (V): V = E/Q (energy in J, charge in C).
    • Current (I): I = Q/t (charge in C, time in s).
    • Ohm's Law: V = IR (resistance in ohms).
  • Resistance: Different materials affect resistance; metals show higher resistance at higher PDS.
  • Components:
    • Diodes and LEDs: Allow current to flow in one direction.
    • LDRs and Thermistors: Resistance changes with light and temperature, respectively.
  • Series Circuits: PD is shared, current is the same.
  • Parallel Circuits: PD is the same, current is shared.
  • Power: P = VI, P = I²R.

Magnetism and Electromagnetism

• Magnets: Permanent (fixed magnetic fields) and Induced (temporary fields when in other magnetic fields).
• Motor Effect: F = BIl (magnetic flux density, current, length).
• Fleming's Left-Hand Rule: Thumb (force), First finger (field), and Middle finger (current).
• Electric Motors: Use split-ring commutators to reverse current direction.
• Generators: Induce current by moving a wire in a magnetic field; used in power stations.
• Transformers: Change voltage levels using coils around an iron core. Vp/Vs = Np/Ns

Particles

• States of Matter: Solid, Liquid, Gas; changes of state involve energy changes.
• Density: ρ = m/V (mass in kg, volume in m³).
• Specific Latent Heat: Energy required to change the state of 1kg of a substance.
• Gas Laws: Pressure and volume relationship P1V1 = P2V2 for a constant temperature.

Exam Tips

• Pause and review complex concepts.
• Understand and apply equations, particularly in rearranging them.
• Conduct practical experiments carefully to avoid systematic and random errors.
• Practice past papers for familiarity with question formats.