Key term
OCR GCSE Combined Science Physics J250
Electricity
Topic overviewCharge, and producing static electricityTransfer of electrons in charging and dischargingCurrent as a rate of flow of chargeCharge, current and timeSeries and parallel circuits, and circuit symbolsCurrent, potential difference and resistanceResistors whose resistance changes, and investigating themLinear and non-linear circuit elements from graphsNet resistance in series and parallelCircuits for measurement, and electrical power
Energy
Topic overviewConservation of energy, and energy storesEnergy changes on heating, and calculating themEnergy of a moving body, a spring and a raised objectDissipation, and energy transfer in domestic devicesPower ratings, efficiency, and increasing itReducing unwanted energy transfer, and the rate of cooling
Forces
Topic overviewMeasuring distance and time, and calculating speedConverting units, and ratesVectors and scalars in motionDistance-time and velocity-time graphsAverage speed, and the equations of uniform motionHow objects interact, and forces as vectorsNewton's first lawResolving forces, and free body diagramsResultant forces, and balanced forcesNewton's second law, and inertiaMomentum and its conservationWork done, and stored energyPower, and Newton's third lawCircular motion and changing velocityStretching, bending and compressing; elastic and plasticForce and extension, linear and non-linearThe spring constant, and work done in stretchingGravitational fields, weight and free fallCalculations with weight and gravitational field strength
Global Challenges
Topic overviewTypical speeds and everyday accelerationsReaction time, stopping distance and the dangers of large decelerationsStopping distance, acceleration and collision force calculationsEnergy resources, and trends in their useThe national grid, and step-up and step-down transformersWhy the national grid is efficient, and power in a transformerMains electricity: a.c., d.c. and the domestic supplyLive, neutral and earth wires, and electrical danger
Magnetism and Magnetic Fields
Matter
Topic overviewHow the atomic model changed, and the structure of the atomThe size of atoms, and defining densityDensity of the states of matter, and density calculationsConservation of mass in changes of stateHeating a system, and specific heat capacityCalculations with specific heat capacity and latent heatGas molecules, temperature and pressure
Radioactivity
Waves in Matter
Topic overviewAmplitude, wavelength, frequency and periodThe wave equationTransverse and longitudinal wavesModelling waves with ripples and soundElectromagnetic waves as transverse, and energy transferFrequency and wavelength across the spectrumWhat our eyes detect, and light as an electromagnetic waveUses of electromagnetic wavesHazards of ultraviolet, X-rays and gamma raysProducing and receiving radio wavesAbsorption, transmission, refraction and reflectionInvestigating reflection and refraction of light
Forces
Force and extension, linear and non-linear
- 2 things to know
- Paper 11 (Physics)
Overview
Extension and how to calculate it, direct proportion up to the limit of proportionality, the elastic limit, linear and non-linear force-extension graphs, and the spring-stretching investigation with its variables, precautions, results table, hypothesis, length against force graph and conclusion.
What you need to know
Answer each one before you reveal it.
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Key term
How is the extension of a spring worked out from its stretched and unstretched lengths?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is meant by the extension of a spring?
Model answer
The increase in its length compared with its original unstretched length.
- 2
How is the extension of a spring worked out from its stretched and unstretched lengths?
Model answer
Subtract the original unstretched length from the stretched length.
- 3
A spring has an unstretched length of 4.0 cm and is 10.0 cm long when loaded. What is its extension?
Model answer
6.0 cm, because 10.0 cm − 4.0 cm = 6.0 cm.
- 4
State the relationship between the force applied to a spring and its extension, provided the limit of proportionality has not been passed.
Model answer
The extension is directly proportional to the force applied.
- 5
The force applied to a spring is doubled and the limit of proportionality is not passed. What happens to the extension?
Model answer
It doubles as well.
- 6
Describe the shape of a graph of force against extension for a spring up to the limit of proportionality.
Model answer
A straight line that passes through the origin.
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