understand that regions of equal temperature are in thermal equilibrium

What is Thermal Equilibrium?

When two or more regions have the same temperature, they are in thermal equilibrium. This means there is no net flow of heat between them. Think of it like two cups of tea at the same temperature – they stay that way unless something changes. 🍵

Key Concepts

• Equal Temperatures: $T_1 = T_2$
• No Net Heat Flow: Heat energy does not move from one region to another.
• Stable State: The system remains unchanged until an external influence is applied.

Examples & Analogies

• Two ice cubes in a glass of water – they stay at the same temperature until one melts.
• Room temperature air and a metal spoon left in the room – both reach the same temperature.
• ⚖️ A balance scale with equal weights on both sides: just like equal temperatures, no net movement.

Mathematical Representation

In a simple two‑region system, thermal equilibrium is expressed as:

$$T_1 = T_2$$

Where $T_1$ and $T_2$ are the temperatures of the two regions.

Temperature Comparison Table

Exam Tips

• Remember the definition: equal temperatures mean no net heat flow.
• Use the symbol $T_1 = T_2$ to show equilibrium in diagrams.
• When given a scenario, check if temperatures are equal before concluding equilibrium.
• Practice sketching temperature profiles – a flat line indicates equilibrium.
• Be careful with units – always state temperature in °C or K when required.