OCR GCSE Physics A key terms

The time taken for the activity of a radioactive sample, or its number of undecayed nuclei, to fall to half its value.

The interval between the lowest and highest sound frequencies that a person can detect.

The transfer of energy from a hotter region to a colder region because of a temperature difference.

A graph showing how the temperature of a substance changes as energy is transferred to it over time.

The unit of frequency; one hertz means one complete cycle per second.

The rule that the extension or compression of an elastic object is directly proportional to the applied force while its force–extension relationship remains linear.

A system that uses pressure transmitted through a liquid to transfer a force from one place to another.

The ray travelling towards a surface or boundary.

A current produced in a complete conducting circuit by an induced potential difference.

A magnetic material that becomes magnetised when placed in an external magnetic field and usually loses most of that magnetism when the field is removed.

A measure of how difficult it is to change the velocity of an object.

The mass defined by the ratio of the resultant force acting on an object to the acceleration it produces.

Sound with a frequency below about 20 Hz, which is normally below the human hearing range.

The speed of an object at one particular moment.

A material, such as plastic or rubber, through which electric charge cannot move easily.

The energy carried by radiation through a unit area each second; greater intensity means a greater rate of energy transfer.

An effect involving two objects in which each object exerts a force on the other.

The two equal and opposite forces produced by one interaction, with one force acting on each of the two interacting objects.

The boundary where two different materials meet.

The total energy stored by the particles within a material, including their microscopic kinetic and potential energy.

A recognised standard system of measurement built from seven base units; those used most often in mechanics include the metre, kilogram and second.

A relationship in which multiplying one quantity by a factor causes the other quantity to be divided by that factor.

An atom or group of atoms with an overall electric charge because it has lost or gained electrons.

The loss of an outer electron from an atom, leaving a positively charged ion.

Radiation with enough energy to remove electrons from atoms or molecules, forming ions.

A material within a transformer that becomes magnetised and links the changing magnetic field from the primary coil to the secondary coil.

Exposure of an object or living thing to radiation from a source.

Atoms of the same element whose nuclei contain the same number of protons but different numbers of neutrons.