THERMAL EXPANSION
THERMAL ENERGY (HEAT CONTENT OF A BODY)
➢ This is the energy possessed by a body due to its temperature.
o Heat content of the body is due to the random motion of the particles that make up the object.
o The thermal energy of an object increases within an increase in temperature.
HEAT
➢ This is a form of energy transferred from one body to another due to difference in temperature
between the two bodies.
TEMPERATURE
➢ This is the degree of hotness or coldness of a body.
❖ When two object having different temperatures are place in contact, their temperatures change
until they reach a thermal equilibrium.
THERMAL EQUILIBRIUM
➢ This is the condition under which two substances in physical contact with each other exchange
no heat energy, because they have equal temperature.
❖ A thermal equilibrium the two objects will be at the some temperature. The thermal
equilibrium is achieved by the flow of thermal energy from the hotter object into the cooler
object until no further exchange of energy.
SOURCES OF THERMAL ENERGY
There are numerous sources of thermal energy. These includes:
a) Sun
b) Fuels
c) Nuclear sources
d) Geothermal sources
THERMAL EXPANSION
➢ This is the change in volume or dimensions of materials as a result of temperature change.
❖ All states matter (solids, liquids and gases) expand when heated.
TYPES OF THERMAL EXPANSION
1) Linear expansion
2) Areal/superficial expansion
3) Cubical/volume expansion
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1) LINEAR EXPANSION
➢ This is the increase in length of materials due to rise in temperature.
2) AREAL/SUPERFICIAL EXPANSION
➢ This is the increase in area of materials due to rise in temperature.
3) CUBICAL/VOLUME EXPANSION
➢ This is the increase in volume of substances due to rise in temperature.
THERMAL EXPANSION OF SOLID
❖ Most solid expand when heated. However, the expansion is so small that it is difficult to
observe when dealing with small objects in the laboratory.
✓ For example, the ball and rig apparatus consists of a brass sphere and brass ring connected to a wooden handle as shown below.
