Physical Science - Thermal Energy & Heat

Bimetallic Strip

Two strips of different metals, such as one of brass and one of iron, welded or riveted together into one strip. Because the two substances expand at different rates, when heated or cooled the strip bends. Used in thermostats.

Celsius Scale

A temperature scale with 0 as the melt-freeze temperature for water and 100 as the boil-condense temperature of water at standard pressure.

Conduction

The transfer of thermal energy by collisions between the particles that make up matter.

Conductor

A material, such as copper wire,through which electrons can move easily.

Convection

The transfer of thermal energy in a fluid by the movement of warmer and cooler fluid from one place to another.

Fahrenheit Scale

The temperature scale in common use in the United States. The number 32 is assigned to the freezing points of water and the number 212 to the boiling point of water.

Greenhouse Effect

The warming effect whose cause is that short-wavelength radiant energy from the sun can enter the atmosphere and be absorbed by Earth more easily than long-wavelength energy from Earth can leave.

Heat

Energy that is transferred between objects due to a temperature difference between those objects.

Internal Energy

The total energy stored in the atoms and molecules within a substance.

Kelvin Scale

A temperature scale whose zero (called absolute zero) is assigned to the lowest temperature possible. 0 K = -273 degrees C. There are no negative numbers on the Kelvin scale.

Newton's Law of Cooling

The rate of cooling an object-whether by conduction, convection or radiation- is approximately proportional to the temperature difference between the object and its surroundings.

Radiant Energy

Energy carried by electromagnetic waves.

Radiation

The transfer of energy by electromagnetic waves.

Solar Collector

A device used in an active solar heating system that transforms radiant energy from the Sun into thermal energy.

Specific Heat

The amount of heat needed to raise the temperature of 1 kg of a material 1 degree Celsius.

Termperature

A measure of the average kinetic energy of all the particles that make up an object.

Thermal Contact

The state of two or more objects or substances in contact such that it is possible for heat to flow from one object or substance to another.

Thermal Equilibrium

The state of two or more objects or substances in thermal contact when they have reached the same temperature.

Thermal Energy

The sum of the kinetic and potential energy of the particles that make up an object.

Thermal Insulator

A material through which thermal energy moves slowly.

Thermostat

A type of valve or switch that responds to changes in temperature and that is used to control the temperature of something.