IGCSE Physics Glossary | CBSE | ICSE | UPSC | Exam reference

IGCSE Physics Glossary – Here we are going to post a physics glossary that can also be referred to by high school physics students to prepare for different boards like GCSE, IGCSE, ICSE, CBSE, and other international boards. Candidates preparing for UPSC exams in India can also refer to this compiled glossary.

Please note that this is a quick compiled version sourced from external online resources and may have some typos. You may send suggestions for rectification to our email id if you find any.


Here goes our GLOSSARY OF PHYSICS TERMS and this is supposed to help the K12 students and candidates appearing for different competitive examinations. This version has some physics terms starting with {A,…,C}

Absolute zero – The theoretical lowest temperature possible, which occurs when all random motion of molecules has ceased.

Acceleration due to gravity – The acceleration produced in a body due to the earth’s attraction is called acceleration due to gravity. It is denoted by the letter g. Its SI unit is m/s². On the surface of the earth, its average value is 9.8m/s². The value of g on the surface of the earth increases in going towards the poles from the equator.
The acceleration due to the gravity of the earth decreases with altitude and with depth inside the earth. The value of g at the center of the earth is zero.

Acceleration – The rate of change of velocity of a moving object is called its acceleration. The SI units of acceleration are m / s². By definition, this change in velocity can result from a change in speed, a change in direction, or a combination of changes in speed and direction.

Alpha particle – The nucleus of a helium atom (two protons and two neutrons) emitted as radiation from a decaying heavy nucleus; also known as an alpha ray.

Alternating current – An electric current that first moves one direction, then the opposite direction with a regular frequency.

Ampere – Unit of electric current. It is equivalent to coulomb/sec.

Amplitude (of waves) – The maximum displacement of particles of the medium from their mean positions during the propagation of a wave is called the amplitude of the wave.

Amplitude (of an oscillation) – The maximum displacement of a body from its mean position during an oscillatory motion is called the amplitude of oscillation.

Angle of incidence – Angle of an incident (arriving) ray or particle to a surface; measured from a line perpendicular to the surface (the normal).

Angle of reflection – Angle of a reflected ray or particle from a surface; measured from a line perpendicular to the surface (the normal).

Atom – The smallest unit of an element that can exist alone or in combination with other elements.

Atomic number – The number of protons in the nucleus of an atom.

Axis – The imaginary line about which a planet or other object rotates.

Balanced Forces – When a number of forces act on a body, and the resultant force is zero, then the forces are said to be balanced forces.

Barometer – An instrument that measures atmospheric pressure, used in weather forecasting and in determining elevation above sea level.

Beat – Rhythmic increases and decreases of volume from constructive and destructive interference between two sound waves of slightly different frequencies.

Beta particle – High-energy electron emitted as ionizing radiation from a decaying nucleus; also known as a beta ray.

Boiling point – The temperature at which a phase change of liquid to gas takes place through boiling. It is the same temperature as the condensation point.

Cathode rays – Negatively charged particles (electrons) that are emitted from a negative terminal in an evacuated glass tube.

Celsius scale of temperature – In the Celsius scale of temperature, the ice-point is taken as the lower fixed point (0 deg C ) and the steam-point is taken as the upper fixed point (100 deg C). The interval between the ice point and the steam point is divided into 100 equal divisions. Thus, the unit division on this scale is 1 deg C.
This scale was earlier called the centigrade scale. 1 deg C = 9/5 deg F.

Centigrade – Alternate name for the Celsius scale.

Centrifugal force – An apparent outward force felt by an object following a circular path. This force is actually a pseudo force. This force is a consequence of the third law of motion.

Centripetal force – The force required to pull an object out of its natural straight-line path and into a circular path; centripetal means towards the center and the direction of this force is towards the center of the circular path.

Circular Motion – The motion of a body along a circular path is called circular motion.

Compression – A part of a longitudinal wave in which the density of the particles of the medium is higher than the normal density is called a compression.

Condensation (water vapor) – Where more vapor or gas molecules are returning to the liquid state than are evaporating.

Condensation point – The temperature at which a gas or vapor changes back to a liquid.

Conduction – The transfer of heat from a region of higher temperature to a region of lower temperature by increased kinetic energy moving from molecule to molecule.

Convection – Transfer of heat from a region of higher temperature to a region of lower temperature by the displacement of high-energy molecules – for example, the displacement of warmer, less dense air with higher kinetic energy by cooler, denser air with lower kinetic energy.

Conventional current – Opposite to electron current – Electrons will flow from the lower potential to the higher potential. This is the direction of electronic flow or electronic current. But, the conventional flow of electric current is directionally opposite to the flow of electrons or electronic flow.

Coulomb Unit used to measure quantity of electric charge; equivalent to the charge resulting from the transfer of 6.24 billion particles such as the electron.

Crest The point of maximum positive displacement on a transverse wave is called a crest.

Critical angle Limit to the angle of incidence in the denser medium beyond which all light rays are reflected internally.

[ Will add more physics terms – coming soon]

IGCSE Physics Glossary | CBSE | ICSE | UPSC | Exam reference
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