Lesson Notes By Weeks and Term v4 - SHS 3
HEAT
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
HEAT
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Physics
Class: SHS 3
Term: 1st Term
Week: 16
Grade code: 3.2.1.LI.2
Strand code: 2
Sub-strand code: 1
Content standard code: 3.2.1.CS.1
Indicator code: 3.2.1.LI.2
Theme: ENERGY
Subtheme: HEAT
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
This lesson explores thermal expansion, which is the tendency of matter to change its shape, area, and volume in response to a change in temperature. We see the effects of thermal expansion all around us in Ghana. Think about the small gaps you see on large bridges like the Adomi Bridge or on railway tracks like the Accra-Tema line. These are not mistakes; they are intentionally designed to allow for expansion on hot, sunny days to prevent the structure from buckling and becoming damaged.
A. The Particulate Nature of Thermal Expansion
When a solid material is heated, the thermal energy supplied is converted into kinetic energy for its constituent atoms or molecules. These particles do not move from place to place, but they vibrate more vigorously about their fixed positions. As they vibrate with greater amplitude, they push their neighbours further apart. This small increase in the average distance between particles, when accumulated over the entire solid, results in a measurable increase in the size (length, area, or volume) of the object. This phenomenon is called thermal expansion. B. Linear Expansion
This refers to the expansion of a solid in one dimension – its length. It is most noticeable in long, thin objects like rods, wires, and railway tracks.
The change in length (ΔL) of a solid is directly proportional to: Its original length (L₁). The change in temperature (ΔT).