38 of the Physics glossary’s terms, each with the part of the syllabus where you first meet it.
The state of a system described by its bulk properties, such as pressure, volume and temperature, or the total number of heads in a set of coins.
A region in which a magnet, a magnetic material or a moving charge experiences a magnetic force.
A line showing the direction in which the north pole of a small compass would point at each point; the lines form closed loops, running from N to S outside a magnet.
For a flat area in a uniform field, , where is the angle between the field and the normal to the area; measured in webers.
The force per unit charge per unit speed on a charge moving at right angles to a magnetic field, ; a vector measured in tesla.
The force a magnetic field exerts on a moving charge, , perpendicular to both the velocity and the field.
One of the two ends of a magnet, north or south, where its field is most concentrated; like poles repel and unlike poles attract, and poles always come in pairs.
The band on the HR diagram, from hot luminous stars to cool dim ones, of stars fusing hydrogen into helium in their cores; stars spend most of their lives on it.
One level of performance in an assessment criterion, described in words together with the marks it can earn.
The difference between the total mass of the separated nucleons of a nucleus and the mass of the nucleus itself.
The mass of matter passing a point per unit time, , in ; the force needed to change the velocity of a stream of matter by is
An instrument that separates ions by their charge-to-mass ratio, using the different radii of their paths in a magnetic field, to measure the masses and abundances of isotopes.
The principle that mass and energy are equivalent, : any change in the energy of a system changes its mass by .
A mass attached to a spring that oscillates with simple harmonic motion of period .
The wave associated with a moving particle, whose wavelength is the de Broglie wavelength .
The steepest and least steep straight lines that pass through every error bar on a graph; half the difference of their gradients is the uncertainty in the gradient.
The solar power per unit area averaged over a planet's whole surface, , because the planet intercepts sunlight over a disc of area but has a surface area .
The sum of the kinetic, gravitational potential and elastic potential energy of a system. It is conserved when no friction or other resistive force does work.
A wave that needs a material medium whose particles oscillate to pass on the disturbance, such as sound, water waves or waves on a string.
The material through which a mechanical wave travels, whose particles oscillate as the wave passes.
The change from solid to liquid at the melting point, during which energy is absorbed at constant temperature.
A way of finding a specific heat capacity, latent heat or temperature by mixing a hot and a cold substance in an insulated container and equating the energy lost by one to the energy gained by the other.
A feature of a method that reduced the accuracy or precision of the data, such as heat loss in calorimetry or variable contact resistance.
The way data are collected or selected to answer a research question, together with the reasons for each choice of technique, apparatus, range and number of measurements.
An 1887 interferometer experiment that looked for a change in the speed of light with the direction of the Earth's motion and found none.
One particular arrangement of all the individual particles of a system that produces a given macrostate; the number of microstates is .
An experiment (1909–1913) in which charged oil drops were held stationary in a uniform electric field, showing that charge is quantised and measuring the elementary charge.
A double-slit or grating maximum that does not appear because it falls on a minimum of the single-slit envelope; for a double slit it happens when equals the order .
Re-marking of a sample of a school's internal assessment by an external examiner, so that every school's marks follow the same standard.
A material of light nuclei, such as water or graphite, that slows fast neutrons to thermal speeds by elastic collisions so that they are more likely to cause fission.
The constant in the ideal gas equation
The mass of one mole of a substance, ; usually quoted in .
The SI unit of amount of substance: one mole contains exactly particles, about .
A measure of a body's resistance to angular acceleration about an axis, depending on how its mass is distributed about that axis; for point masses, measured in .
Made of single atoms rather than molecules of several atoms, as in helium, neon and argon.
Describes light (or another wave) of a single wavelength and frequency.
The force on a current-carrying conductor in a magnetic field, , used in electric motors and loudspeakers.
An unstable subatomic particle, like a heavy electron, with a mean lifetime of at rest; muons made by cosmic rays provide evidence for time dilation.