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
Radioactivity
Unstable nuclei and the emissions they give out
- 3 things to know
- Paper 12 (Physics)
Overview
Why unstable nuclei emit radiation, what alpha and beta particles, gamma rays and neutrons are and the charge each carries, and how the mass number and atomic number change with each emission, including why beta emission leaves the mass number unchanged.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What is a beta particle?
Key term
Which of the emissions from an unstable nucleus carries neither charge nor mass?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why does a nucleus emit radiation?
Model answer
Because it is unstable, and emitting radiation makes it more stable.
- 2
What is an alpha particle made of?
Model answer
An alpha particle is two protons and two neutrons, which is the same as a helium nucleus.
- 3
What is a beta particle?
Model answer
A beta particle is a fast-moving electron thrown out of the nucleus.
- 4
What kind of radiation is a gamma ray?
Model answer
It is high-frequency electromagnetic radiation emitted from the nucleus, not a particle.
- 5
Apart from α particles, β particles and γ rays, what else can an unstable nucleus emit?
Model answer
It can emit a neutron.
- 6
What is the charge on an alpha particle?
Model answer
It has a charge of +2, because it carries two protons and no electrons.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Radioactivity, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.