OCR GCSE Physics A key terms

A calibrated spring instrument used to measure force, including weight, in newtons.

The law relating an object's resultant force, mass and acceleration: $F=ma$.

The law stating that whenever object A exerts a force on object B, object B simultaneously exerts an equal-magnitude force in the opposite direction on object A.

A force that acts between objects without them touching.

An interaction that can occur when the objects are separated, through a field.

A circuit element whose current is not directly proportional to the potential difference across it, giving a curved current–potential difference graph.

A relationship whose graph is curved, so its gradient changes.

A finite source of energy that is not replaced on a human timescale, such as coal, oil, gas or nuclear fuel.

An energy resource with a finite supply that is not replaced as quickly as people use it.

Motion in which an object's speed, direction, or both change during the journey.

At right angles to a surface.

A contact force exerted by a surface on an object, acting away from and perpendicular to the surface.

A force acting at 90° to a surface.

A temperature-sensitive resistor whose resistance falls as its temperature rises.

The total positive charge of a nucleus, produced by all of its protons.

A symbolic statement of a nuclear change in which mass number and charge balance on the two sides.

The splitting of an unstable atomic nucleus into smaller nuclei, releasing energy.

The joining of light atomic nuclei to form a heavier nucleus, releasing energy.

The standard way of showing an element symbol together with its mass number and atomic number.

A compact representation of a nucleus showing its element symbol, mass number and atomic number, written $^{A}_{Z}\mathrm{X}$.

The tiny, positively charged central region of an atom, containing protons and neutrons and almost all the atom's mass.

A particular type of nucleus specified by its numbers of protons and neutrons.

The number of complete loops of wire in a transformer coil.

The unit of resistance, with symbol Ω.

A conductor that has constant resistance when its temperature and other physical conditions remain constant.

A thin strand of glass or plastic along which visible or infrared signals can be guided.

The distance from the centre of the body being orbited to the orbiting object.

The speed at which an object moves along its orbital path.