physics gcse edexcel paper 1

absorb

To soak up or take in - for waves, it is when the wave disappears as the energy it is carrying is transferred to a material.

absorb

To soak up or take in.

Absorb

When a wave disappears as the energy it is carrying transfers to the medium through which it is travelling.

absorption spectrum

A spectrum of light (or other electromagnetic radiation) that includes black lines. These are caused by some wavelengths being absorbed by the materials that the light (or radiation) passes through.

acceleration

A measure of how quickly the velocity of something is changing. It can be positive if the object is speeding up or negative if it is slowing down. It is a vector quantity.

acceleration

A measure of how quickly the velocity of something is changing. It can be positive if the object is speeding up or negative if it is slowing down.

action-reaction forces

Pairs of forces on interacting objects. They are always the same size, in opposite directions, and acting on different objects. They are not the same as balanced forces.

activity

The number of emissions of ionising radiation from a sample in a given time. Usually given in becquerels (Bq).

alpha particle

A particle made of two protons and two neutrons, emitted as ionising radiation from some radioactive isotopes.

alpha particle

A particle made of two protons and two neutrons, emitted as ionising radiation from some radioactive isotopes.

Amplify

To make bigger.

Amplitude

The size of vibrations or the maximum distance a particle moves away from its resting position when a wave passes.

angle of incidence

The angle between an incoming light ray and the normal.

angle of reflection

The angle between the normal and a ray of light that has been reflected.

angle of refraction

The angle between the normal and a ray of light that has been refracted.

artificial satellite

A satellite made by humans.

asteroid

A small lump of rock orbiting the Sun.

atom

The smallest neutral part of an element that can take part in chemical reactions.

atomic energy

A name used to describe energy when it is stored inside atoms. Another name for 'nuclear energy'.

atomic number

The number of protons in the nucleus of an atom. It is also known as the proton number.

Auditory nerve

The nerve that carries impulses from an ear to the brain.

average speed

The speed worked out from the total distance travelled divided by the total time taken for a journey.

background radiation

Ionising radiation that is around us all the time from a number of sources. Some is naturally occurring, but some comes from human activities.

balanced forces

Forces acting on the same object. They are always equal, in opposite directions, and always act on the same object. They do not have to be the same type of force. An object acted on by these forces will not change the way it is moving..

balanced forces

When the forces in opposite directions on an object are the same size so that there is a zero resultant force.

becquerel

The units for the activity of a radioactive object. Equal to one radioactive decay per second.

beta particle

A particle of radiation emitted from the nucleus of a radioactive atom when it decays. It is an electron.

Big Bang theory

The theory that the Universe began from a tiny point with huge energy, and has been expanding ever since.

biofuel

A fuel made from plants or animal wastes.

black hole

Core of a red supergiant that has collapsed. Black holes are formed if the remaining core has a mass more than three or four times the mass of the Sun.

braking distance

The distance travelled by a vehicle while the brakes are working to bring it to a halt.

centripetal force

A force that causes objects to follow a circular path. The force acts towards the centre of the circle.

chain reaction

The sequence of reactions produced when a nuclear fission reaction triggers one or more further fissions.

chemical energy

A name used to describe energy when it is stored in chemical substances. Food, fuel and batteries all store this.

climate change

Changes that will happen to the weather as a result of global warming, which is caused by the increase in the amount of carbon dioxide in the atmosphere.

climate change

Changes that will happen to the weather as a result of global warming, which is caused by the increase in the amount of carbon dioxide in the atmosphere.

Cochlea

The part of the ear that changes vibrations into electrical impulses.

comet

A small lump of dirty ice orbiting the Sun

conduction

The way energy is transferred through solids by heating. Vibrations are passed on from particle to particle.

conservation of momentum

The total momentum of moving objects before a collision is the same as the total momentum afterwards, as long as no external forces are acting.

contaminate

An unwanted addition that makes something unsuitable or impure.

control rod

A rod that can be lowered into the core of a nuclear reactor to absorb neutrons and slow down the nuclear chain reaction.

convection

The movement of particles in a fluid (gas or liquid) depending on their temperature. Hotter, less dense regions rise, and cooler, denser regions sink.

converging lens

A lens that brings together light rays.

core

The innermost part of something.

cosmic microwave background radiation

Microwave radiation received from all over the sky, originating at the Big Bang. Abbreviated CMBR.

cosmic rays

Charged particles with a high energy that come from stars, neutron stars, black holes and supernovae.

count rate

The number of alpha or beta particles or gamma rays detected by a Geiger-Müller tube in a certain time.

critical angle

The angle of incidence above which total internal reflection occurs inside a material such as glass or water.

crumple zone

A vehicle safety device in which part of the vehicle is designed to collapse in a crash, reducing the force of the impact.

daughter nucleus

A nucleus produced when the nucleus of an unstable atom splits into two during fission or when a radioactive nucleus decays by emitting an alpha or beta particle.

decay

When an unstable nucleus changes by giving out ionising radiation to become more stable.

deceleration

slowing down - a negative acceleration

deceleration

When an object is slowing down.

decommission

To dismantle safely.

diffuse reflection

Reflection from a rough surface, where the reflected light is scattered in all directions.

displacement

The distance travelled in a particular direction. It is a vector, distance is not.

dissipated

Spread out.

distance

How far something has travelled. It is a scalar, and has no direction.

distance/time graph

A graph of the distance travelled against time for a moving object. The gradient of the line gives the speed.

diverging lens

A lens that spreads out light rays.

DNA

Deoxyribonucleic acid. Chemical that makes up genes and chromosomes. It contains the instructions for a cell's growth and activity.

Doppler effect

The change in the pitch of a sound heard when the source of sound is moving relative to the observer.

dose

The amount received at one time - for example, the amount of radiation a person receives.

dwarf planet

A rocky body orbiting the Sun that is not quite big enough to be called a planet (e.g. Pluto).

Ear canal

The tube in the head that leads to the eardrum.

Ear drum

A thin membrane inside the ear that vibrates when sound reaches it.

efficiency

A way of saying how little energy something wastes.

elastic potential energy

A name used to describe energy when it is stored in stretched or squashed things that can change back to their original shapes. Another name for 'strain energy'.

electromagnetic radiation

A form of energy transfer, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays.

electromagnetic radiation

A form of energy transfer, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays.

electromagnetic spectrum

The entire frequency range of electromagnetic waves.

electromagnetic waves

A group of waves that all travel at the same speed in a vacuum, and are all transverse.

Electromagnetic waves

A group of waves that all travel at the same speed in a vacuum, and are all transverse.

electron

A tiny particle with a negative charge and very little mass.

electron shell

Area around a nucleus that can be occupied by electrons. Usually drawn as circles. Also called an electron energy level or an orbit.

electronic configuration

The arrangement of electrons in shells around the nucleus of an atom.

electrostatic repulsion

A force between two electrical charges that have the same sign, which pushes them apart.

element

A simple substance made up of only one type of atom.

elliptical

A shape like a squashed circle.

emission spectrum

A set of wavelengths of light or other electromagnetic radiation showing which wavelengths have been given out (emitted) by a substance.

emit

To give out.

equilibrium

When a situation is not changing because all the things affecting it balance out.

external radiotherapy

Treatment of cancer by sending radiation into the body from outside.

filter

Something that only transmits certain colours and absorbs the rest.

fluid

A liquid or a gas.

fluorescence

Absorbing radiation of one wavelength and re-emitting the energy at a different wavelength (usually so that it becomes visible).

focal length

The distance from a lens to the focal point

focal point

The point at which parallel light rays converge after passing through a converging lens, or appear to come from after passing through a diverging lens.

force

At the simplest level it is a push, pull or twist. When they act on an object they can cause it to accelerate. It is a vector quantity.

fossil fuel

A fuel formed from the dead remains of organisms over millions of years (e.g. coal, oil or natural gas).

fossil fuel

A fuel formed from the dead remains of organisms over millions of years (e.g. coal, oil or natural gas).

frequency

The number of vibrations (or the number of waves) per second. One hertz (Hz) is one wave per second.

Frequency

The number of vibrations (or the number of waves) per second.

fuel rod

A rod containing the nuclear fuel for a nuclear reactor.

fusion reaction

The reaction when the nuclei of light atoms, such as hydrogen, combine to make the nucleus of a heavier atom.

gamma camera

A camera that detects gamma rays.

gamma ray

A high-frequency electromagnetic wave emitted from the nucleus of a radioactive atom.

gamma rays

Electromagnetic radiation with the shortest wavelengths and highest frequencies.

Geiger-Müller (GM) tube

A device that can detect ionising radiation and is used to measure the activity of a radioactive source.