What are the two possible effects of heating a system?

It can raise the temperature of the system, or it can produce a change of state.

What is meant by the internal energy of a substance?

It is the total energy of all its particles, held both in their movement and in the forces between them.

What happens to the particles of a substance as its temperature rises?

They move faster, so their average kinetic energy increases.

A beaker of water is heated steadily. Its temperature rises until it boils and then stops rising. Explain why.

Before boiling the energy raises the kinetic energy of the particles, but at the boiling point it separates the particles instead, so the temperature holds steady.

OCR GCSE Physics A J249

Electricity

Topic overview Charge, and producing static electricity Transfer of electrons, and electric fields Current as a rate of flow of charge Charge, current and time Series and parallel circuits, and circuit symbols Current, potential difference and resistance Resistors whose resistance changes, and investigating them Linear and non-linear circuit elements from graphs Net resistance in series and parallel Circuits for measurement, and electrical power

Energy

Topic overview Conservation of energy, and energy stores Energy changes on heating, and calculating them Energy of a moving body, a spring and a raised object Dissipation, and energy transfer in domestic devices Power ratings, efficiency, and increasing it Reducing unwanted energy transfer, and the rate of cooling

Forces

Topic overview Measuring distance and time, and calculating speed Converting units, and rates Vectors and scalars in motion Distance-time and velocity-time graphs Average speed, and the equations of uniform motion How objects interact, and forces as vectors Newton's first law Resolving forces, and free body diagrams Resultant forces, and balanced forces Newton's second law, and inertia Momentum, and force as a change in momentum Work done, and stored energy Power, and Newton's third law Circular motion and changing velocity Stretching, bending and compressing; elastic and plastic Force and extension, linear and non-linear The spring constant, and work done in stretching Gravitational fields, weight and free fall Calculations with weight and gravitational field strength Turning forces and the moment of a force Levers and gears Pressure in fluids, and the force on a surface

Global Challenges

Topic overview Typical speeds and everyday accelerations Reaction time, stopping distance and the dangers of large decelerations Estimating stopping distances and the forces in a collision Energy resources, and trends in their use The national grid, and step-up and step-down transformers Why the national grid is efficient, and the transformer equation Mains electricity: a.c., d.c. and the domestic supply Live, neutral and earth wires, and electrical danger Red-shift and the Big Bang The formation of the Sun, and radiation from bodies The solar system Circular orbits and stable orbits Radiation and the temperature of a body, and seismic waves and sonar

Magnetism and Magnetic Fields

Topic overview Permanent and induced magnets, and magnetic poles Magnetic fields, and the dipping compass The magnetic effect of a current, and solenoids The motor effect and Fleming's left-hand rule The force on a conductor, and how a motor turns Induced potential, alternators and dynamos Transformers and the turns ratio The microphone

Matter

Topic overview How the atomic model changed, and the structure of the atom The size of atoms, and defining density Density of the states of matter, and density calculations Conservation of mass in changes of state Heating a system, and specific heat capacity Calculations with specific heat capacity and latent heat Gas molecules, temperature and pressure Compressing a gas, and changing its volume Doing work on a gas Atmospheric pressure and why it varies with height Floating, sinking and pressure in a liquid

Radioactivity

Topic overview Protons, neutrons and isotopes Unstable nuclei and the emissions they give out Balancing nuclear equations Electron energy levels, and radiation from atoms Half-life and the randomness of decay Penetration of alpha, beta and gamma Contamination and irradiation, and half-life as a hazard Uses of nuclear radiation Nuclear fission and fusion

Waves in Matter

Topic overview Amplitude, wavelength, frequency and period The wave equation Transverse and longitudinal waves Sound crossing a boundary; reflection, transmission and absorption Converting sound to vibrations, and the range of hearing Modelling waves with ripples and sound Electromagnetic waves as transverse, and energy transfer Frequency and wavelength across the spectrum What our eyes detect, and light as an electromagnetic wave Uses of electromagnetic waves Hazards of ultraviolet, X-rays and gamma rays Exploring structures with waves, and producing radio waves Absorption, transmission, refraction and reflection Ray diagrams for reflection and refraction How colour arises

Matter

Heating a system, and specific heat capacity

3 things to know
Paper 3

Overview

The two effects of heating a system, internal energy and particle speed, why the temperature holds steady during a change of state, specific heat capacity and the specific latent heats of fusion and vaporisation with their units and when each is used, and the flat section of a cooling curve for stearic acid.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Which energy store increases when a system is heated?

Key term

Why does the temperature stay constant while a substance is changing state, even though heating continues?

Key term

How does cooling a system change its internal energy?

Questions from this subtopic

Each one with the model answer underneath.

1
What are the two possible effects of heating a system?
Model answer
It can raise the temperature of the system, or it can produce a change of state.
2
Which energy store increases when a system is heated?
Model answer
The internal energy store of the system.
3
What is meant by the internal energy of a substance?
Model answer
It is the total energy of all its particles, held both in their movement and in the forces between them.
4
What happens to the particles of a substance as its temperature rises?
Model answer
They move faster, so their average kinetic energy increases.
5
Why does the temperature stay constant while a substance is changing state, even though heating continues?
Model answer
The energy supplied is used to overcome the forces holding the particles together rather than to make the particles move faster.
6
A beaker of water is heated steadily. Its temperature rises until it boils and then stops rising. Explain why.
Model answer
Before boiling the energy raises the kinetic energy of the particles, but at the boiling point it separates the particles instead, so the temperature holds steady.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book

2Open book

3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Electricity

Energy

Forces

Global Challenges

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Mass × .

velocityaccelerationweight

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AGamma radiation is the most penetrating.

BAlpha radiation is the least penetrating.

CAlpha radiation is the most strongly ionising.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Current means the rate of flow of electric charge.

TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Matter, 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.

Start revising, £5 a month See how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.