Mini Physics
Part of Mini EducationSwitch subject
Search

A Level Energy & Fields Hub

Build a syllabus-aligned route through energy stores and transfers, work, kinetic and potential energy, fields, elastic energy, power and efficiency.

  • GCE A-Level H2 Physics 2027
Learning goals
  • Track energy stores and transfers, then apply conservation of energy.
  • Define work and derive and apply the kinetic-energy relationship.
  • Derive Eₖ = ½mv² from the definition of work done by a force and the uniformly accelerated motion equations.
  • Represent fields and relate work done by a field to potential-energy change.
  • Draw field-line representations of uniform and radial gravitational and electric fields.
  • Use force–extension graphs to determine elastic potential energy.
  • Apply power, mechanical power and efficiency relationships.

Energy is tracked through stores and transfers. Fields provide forces and potential-energy stores; work, power and efficiency describe how those transfers occur and how quickly useful output is produced.

Start here

Prerequisites:

Study order: follow the learning path above. It begins with conservation, builds the work–kinetic-energy connection, introduces fields and potential energy, then completes the topic with elastic energy, power, efficiency and system-boundary reasoning.

Know the syllabus boundary

Syllabus 9478 requires energy stores and transfers, work, kinetic energy, field concepts, potential energy, elastic energy from force–extension area, power and efficiency. Detailed gravitational and electric field equations are developed later in their dedicated topics; this hub establishes the common field language first.

Lessons

Work through these lessons in order.

  1. Energy stores, work and kinetic energy
  2. Fields and potential-energy change
  3. Potential energy, power and efficiency
  4. Energy Stores, Transfers & Conservation

    Track energy stores and transfers, define a system boundary, and apply conservation of energy without treating dissipated energy as destroyed.

  5. Work & Kinetic Energy

    Define work using the force component along displacement, derive kinetic energy from work and constant-acceleration equations, and apply the work–energy theorem.

  6. Fields, Work & Potential Energy

    Define gravitational and electric fields, read field lines and equipotentials, and relate work done by a field to potential-energy change.

  7. Elastic Potential Energy (Force–Extension Graph)

    Determine work done and elastic potential energy from force–extension area, using one-half kx squared only in the Hooke's-law region.

  8. Power & Efficiency

    Define power as an energy-transfer rate, apply mechanical power as force times velocity component, and solve energy and power efficiency problems.

  9. System Boundaries & Interactions · Supporting

    Choose a system boundary, classify interactions as internal or external, and connect external force, momentum change and energy transfer.

Revision

Quick reference
  • Conservation: total energy is constant for an isolated system; the distribution among stores may change.
  • Constant-force work: W = Fs cos θ, where θ is the angle between force and displacement.
  • Kinetic energy: Eₖ = (1/2)mv² and net work Wₙₑₜ = Δ Eₖ.
  • Field work: W_field = -Δ U.
  • Elastic energy: area under the force–extension graph; frac12kx² only when F = kx from the origin.
  • Power: P = (Δ E)/(Δ t) and P = Fv cos θ.
  • Efficiency: η = (useful output)/(total input) using energy or power consistently.
Problem templates

Energy balance

  1. State the system and the initial and final states.
  2. List the energy stores that change and transfers crossing the boundary.
  3. Write one conservation equation before substituting values.
  4. Check that every term is an energy in joules and that dissipated energy is accounted for.

Work and fields

  1. State the displacement and the relevant force component.
  2. Use W = Fs cos θ for a constant force.
  3. For net work, set Wₙₑₜ = Δ Eₖ.
  4. For work by a field, use W_field = -Δ U and check the sign physically.

Power and efficiency

  1. Decide whether the data describe energy per time or force at a velocity.
  2. Use P = Δ E/Δ t or P = Fv cos θ.
  3. Divide useful output by total input; the result must lie from 0 to 1, or 0% to 100%.
Top exam traps
  1. Energy is not destroyed: resistive interactions transfer mechanical energy to internal energy stores.
  2. Work uses a component: a force perpendicular to displacement does zero work.
  3. Field-work sign: if a field does positive work, the associated potential energy decreases.
  4. Graph area: frac12Fx applies only to a straight line from the origin; otherwise use the actual area.
  5. Power is a rate, not an energy: watts are joules per second.
  6. Efficiency denominator: use total input, not wasted output.

Practice

Quiz, then structured practice

Use the Energy & Fields topic quiz to check work, elastic energy, power and system reasoning. Then complete the structured Work, Energy & Power set without notes. Review field fundamentals again before the dedicated gravitational- and electric-field topics.

Next hub: Circular Motion

Back to A-Level Physics

Continue with the next resource in this course.

Course and syllabus information
Course
GCE A-Level H2 Physics
Edition
GCE A-Level H2 Physics 2027