ALL DEFINITIONS PAPER 1 Flashcards
System
An object or group of objects
Kinetic energy
The energy of a moving object.
Elastic potential energy
: The energy stored in a stretched spring (or another elastic object).
Gravitational potential energy
The energy of an object due to its position in a gravitational
field.
Specific heat capacity
The amount of energy required to raise the temperature of one
kilogram of a substance by one degree Celsius.
Power
The rate at which energy is transferred or the rate at which work is done
Conservation of energy
Energy can be transferred usefully, stored or dissipated, but cannot be
created or destroyed
Dissipated energy
Energy that is stored in less useful ways, often described as being ‘wasted’
Efficiency
The proportion of the total energy input that is transferred usefully.
Renewable energy resource
: An energy resource that is being (or can be) replenished as it is
used
Electric current:
A flow of electrical charge
Potential difference (pd)
The work done per unit charge as the charge passes through a
component
Thermistor
A resistor whose resistance changes with temperature
Light-dependent resistor (LDR)
A resistor whose resistance changes with light intensity
Series circuit:
A circuit where components are connected one after another in a single loop, so
the same current flows through each.
Parallel circuit:
A circuit where components are connected in separate branches, so the current is shared between the branches and the potential difference across each component is the same.
Direct current (dc):
An electric current that flows in one direction only
Alternating current (ac)
: An electric current that repeatedly reverses its direction.
Neutral wire:
: One of the wires in a mains electricity supply that completes the circuit and is at
or close to earth potential (0 V).
Live wire
One of the wires in a mains electricity supply that carries the alternating potential
difference from the supply.
Earth wire:
: A safety wire in a mains electricity supply that is at 0 V and only carries a current if
there is a fault.
National Grid:
: A system of cables and transformers linking power stations to consumers.
Electric field:
: A region around a charged object where another charged object experiences a
force.
Density
The mass per unit volume of a material.
Internal energy
The total kinetic energy and potential energy of all the particles that make up
a system.
Specific latent heat of fusion:
The energy required to change a substance from solid to liquid
Specific latent heat of vaporisation
The energy required to change a substance from liquid to
vapour
Nucleus (of an atom):
The central part of an atom containing protons and neutrons
Atomic number
The number of protons in the nucleus of an atom of an element.
Mass number:
The total number of protons and neutrons in the nucleus of an atom
Isotopes
Atoms of the same element that have different numbers of neutrons.
Ion
An atom or molecule that has gained or lost one or more electrons, giving it an overall
electric charge.
Radioactive decay:
: The process by which unstable atomic nuclei spontaneously break down, emitting radiation
Alpha particle (α):
: A type of radioactive emission consisting of two protons and two neutrons
(a helium nucleus).
Beta particle (β):
A high-speed electron ejected from the nucleus during radioactive decay.
Gamma ray (γ)
: Electromagnetic radiation emitted from the nucleus during radioactive decay
Half-life:
The time it takes for the number of nuclei of a radioactive isotope in a sample to
halve, or the time it takes for the count rate to fall to half its initial level.
Radioactive contamination:
The unwanted presence of materials containing radioactive atoms on other materials
Irradiation
: The process of exposing an object to nuclear radiation; the object does not become radioactive
Background radiation
Low-level radiation that is around us all the time from natural and manmade sources
Nuclear fission:
The splitting of a large and unstable atomic nucleus
Nuclear fusion
The process by which two light atomic nuclei join to form a heavier nucleus,
releasing energy.
