Physics - Practical -2

To demonstrate how a thermometer works by showing how liquid expands when heated and contracts when cooled.

 Materials Required:

- Clinical thermometer

- 2 bowls/beakers:

 - Warm water (about 40–45°C; warm, not hot)

 - Cold water (ice water works best)

- Tissue/cloth

 Procedure:

1. Check the thermometer level

2. Cold water (contraction)

   - Put only the bulb of the thermometer into the cold water.

   - Wait 1 minute and read it temperature level.

   - You will see a lower temperature, meaning the liquid level is lower (contracted).

 4. Warm water (expansion)

   - Put only the bulb into the warm water.

   - Wait 1 minute.

   - You will see a higher temperature, meaning the liquid level is higher (expanded).

 Observation:

- In cold water, the liquid column goes down (contracts).

- In warm water, the liquid column goes up (expands).

 Conclusion

A clinical thermometer works because the liquid inside expands when heated (rises in the tube) and contracts when cooled (falls in the tube).