IGCSE Physics key definitions thermal physics

Download PDF

IGCSE Physics Key Definitions For 0625 AND 0972

By the end of this section, you will be able to :

Define key terms for IGCSE Physics for 0625 and 0972 (9-1) for thermal physics
Understand how marks have been allotted in the examination questions for defining various quantities
Become extremely confident in defining various terms using the correct scientific vocabulary as per the syllabus requirements for thermal physics

2.1 Kinetic particle model of matter

Define Brownian motion: It is the random movement of larger particles, due to their collision with faster moving, smaller particles.
Define Absolute scale of temperature: A temperature scale, whose 0⁰C is equivalent to -273.15 °C (absolute zero) and whose 373.150C is equivalent to 100⁰C.
Define Absolute zero: Absolute zero is the temperature at which a thermodynamic system has the lowest energy. This temperature corresponds to -273.15⁰C on a Celsius temperature scale.
State Boyle's law: For a fixed mass of a gas at constant temperature, the volume varies inversely as the pressure. Hence pv=constant; where p=pressure on the gas and v=volume of the gas.

2.2 Thermal properties and temperature

Define Thermal expansion: Thermal expansion is the expansion of an object under the influence of heat
Define Specific heat capacity:It is the amount of heat energy , needed to raise the temperature of unit mas of a substance through 1⁰C
Define Melting point: It is the temperature at which a solid changes into a liquid
Define Boiling point: It is the temperature at which a liquid changes into a gas, without a rise in temperature.
Define Evaporation: It is the temperature at which a liquid changes into a gas, over a range of temperatures

2.3 Transfer of thermal energy

Define Good thermal conductors (bad thermal insulators): Substances that allow the heat energy to flow through them easily are called as good thermal conductors.
Define Bad thermal conductors ( good thermal insulators):Substances that do not allow the heat energy to flow through them easily are called as good thermal insulators.
Define Conduction:Conduction is the the transfer of energy through the movement of particles that are touching each other.
Define Convection:Convection is a process of heat transfer involving density differences within molecules of the same fluid , in which the warmer and less dense portions rise up, while the more dense and the heavier ones sink down.
Define Radiation:Radiation refers to the process of transmission or emission of energy in the form of waves that can travel through vacuum, meaning they do not require any medium.