AQA Physics paper 1 keyword megaset

activity

the number of unstable atoms that decay per second in a radioactive source

alpha radiation (α)

alpha particles, each composed of two protons and two neutrons, emitted by unstable nuclei

atomic number

the number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number

beta radiation (β)

beta particles that are high energy electrons created in, and emitted from, unstable nuclei

chain reaction

reactions in which one reaction causes further reactions, which in turn cause further reactions, etc.

count rate

the number of counts per second detected by a Geiger counter

gamma radiation (γ)

electromagnetic radiation emitted from unstable nuclei in radioactive substances

half-life

average time taken for the number of nuclei of the isotope (or mass of the isotope) in a sample to halve

ionisation

any process in which atoms become charged

irradiated

an object that has been exposed to ionising radiation

isotopes

atoms with the same number of protons and different numbers of neutrons

mass number

the number of proton and neutrons in a nucleus

moderator

substance in a nuclear reactor that slows down fission neutrons

nuclear fission

the process in which certain nuclei (uranium-235 and plutonium-239) split into two fragments, releasing energy and two or three neutrons as a result

nuclear fission reactor

reactors that release energy steadily due to the fission of a suitable isotope, such as uranium-235

nuclear fusion

the process where small nuclei are forced together to fuse and form a larger nucleus

radioactive contamination

the unwanted presence of materials containing radioactive atoms on other materials

reactor core

the thick steel vessel used to contain fuel rods, control rods and the moderator in a nuclear fission reactor

boiling point

temperature at which a pure substance boils or condenses

melting point

temperature at which a substance melts or solidifies

Boyle's Law

for a fixed mass of gas at constant temperature, its pressure multiplied by its volume is constant

density

mass per unit volume of a substance

freezing point

the temperature at which a pure substance freezes

internal energy

the energy of the particles of a substance due to their individual motion and positions

latent heat

the energy transferred to or from a substance when it changes its state

melting point

temperature at which a pure substance melts or freezes (solidifies)

physical change

a change in which no new substances are produced

pressure

force per unit cross-sectional area for a force acting on a surface at right angles to the surface. The unit of pressure is the pascal (Pa) or newton per square metre (N/m2). p = F/A

specific latent heat of fusion Lf

energy needed to melt 1 kg of a substance with no change of temperature

specific latent heat of vaporisation Lv

energy needed to boil away 1 kg of a substance with no change of temperature

alternating current (a.c.)

electric current in a circuit that repeatedly reverses its direction

direct current (d.c.)

electric current in a circuit that is in one direction only

earth wire

the wire in a mains cable used to connect the metal case of an appliance to earth. Green and yellow

fuse

a fuse contains a thin wire that melts and cuts the current off if too much current passes through it

live wire

the mains wire that has a voltage that alternates in voltage (between +325 V and -325 V in Europe). Brown

neutral wire

the wire of a mains circuit that is earthed at the local substation so its potential is close to zero Blue

oscilloscope

a device used to display the shape of an electrical wave

plugs

a plug has an insulated case and is used to connect the cable from an appliance to a socket

step-down transformers

electrical device used to step-down the size of an alternating potential difference

step-up transformers

electrical device used to step-up the size of an alternating potential difference

three-pin plug

a three-pin plug has a live pin, a neutral pin and an earth pin

biofuel

any fuel taken from living or recently living materials, such as animal waste

carbon-neutral

a biofuel from a living organism that takes in as much carbon dioxide from the atmosphere as is released when the fuel is burned

geothermal energy

energy released by radioactive substances deep within the Earth

national grid

the network of cables and transformers used to transfer electricity from power stations to consumers (i.e., homes, shops, offices, factories etc.)

nuclear fuel

substance used in nuclear reactors that releases energy due to nuclear fission

nucleus

tiny positively charged object composed of protons and neutrons at the centre of every atom

reactor core

the thick steel vessel used to contain fuel rods, control rods and the moderator in a nuclear fission reactor

renewable energy

energy from natural sources that is always being replenished so it never runs out

the radiation emitted by a perfect black body (a body that absorbs all the radiation that hits it)

black body radiation

electromagnetic waves between visible light and microwaves in the electromagnetic spectrum

infrared radiation

energy needed to raise the temperature of 1 kg of a substance by 1 °C. Units are J/kgoC

specific heat capacity

property of a material that determines the energy transfer through it by conduction

thermal conductivity

Battery

Switch open

Switch closed

Filament bulb

Fuse

L.E.D

Resistor

Variable Resistor

Ammeter

Volts

Diode

Light Dependent (L.D.R)

Thermistor

Electric Current (Amps)

The flow of an electric charge. The unit of this is ampere (A)

Potential difference (Voltage

Is the driving force that pushes the charge around. Measured in volts (V)

Resistance

Anything that slows down the flow of the current. Measured in ohms

Rate of the flow of charge

When current flows part a ceartin pointfor a ceartin lenght and time. Measured in coulombs (Q).
In the equation Q=current(I)XTime(t) in seconds

Ammeter

Measures the current in Amps. Must always be connected in the series.

Voltmeter

Measures the voltage in volts. Only able to measure the voltage when connected in a parallel.

Resistance

The longer the length of wire the higher the resistance goes up in solid line. Resistance all adds up

Filament light bulb

The higher the temperate the higher the resistance

Diode

Flows fine in one way but has a very high resistance in the other

Light Dependent Resistor (L.D.R)

Dependent on the intensity of light. In bright light the resistance fall. In darkness the resistance increases

Thermistor

A temperature dependent resistor. In hot conditions, the resistance drops. In cool conditions the resistance rises. Useful in car engine sensors to turn the engine off if it reaches a certain point

diode

a non-ohmic conductor that has a much higher resistance in one direction (its reverse direction) than in the other direction (its forward direction)

electric field

a charged object (X) creates an electric field around itself, which causes a non-contact force on any other charged object in the field

electrons

tiny negatively charged particles that move around the nucleus of an atom

ion

a charged atom or molecule

light-depending resistor (LDR)

a resistor whose resistance depends on the intensity of the light incident on it

light-emitting diode (LED)

a diode that emits light when it conducts

line of force in an electric field

line along which a free positive charge moves long in an electric field

neutrons

uncharged particles of the same mass as protons. The nucleus of an atom consists of protons and neutrons

Ohm's law

the current through a resistor at constant temperature is directly proportional to the potential difference across the resistor

parallel

components connected in a circuit so that the potential difference is the same across each one

potential difference

a measure of the work done or energy transferred to the lamp by each coulomb of charge that passes through it. The unit of potential difference is the volt (V)

protons

positively charged particles with an equal and opposite charge to that of an electron

resistance

resistance (in ohms, Ω) = potential difference (in volts, V) ÷ current (in amperes, A), R = V/I

series

components connected in a circuit in such a way that the same current passes through them

static electricity

electric charge stored on insulated objects

thermistor

a resistor whose resistance depends on the temperature of the thermistor

Students should use numbers given in the question to work out the answer.

Calculate

Select from a range of alternatives.

Choose

This requires the student to describe the similarities and/or differences between things, not just write about one.

Compare

Answers should be written in the space provided, for example on a diagram, in spaces in a sentence, or in a table.

Complete

Specify the meaning of something.

Define

Students may be asked to recall some facts, events or process in an accurate way.

Describe

Set out how something will be done.

Design