Thermometer

1. A thermometer is an instrument to measure temperature.

2. Units for temperature are : a) degrees  Celsius  ( °C )
                                                        b) degrees Fahrenheit  ( °F )


3. A thermometer consists of a narrow glass tube with a bulb at the tip.

Thermometer

4. The bulb is filled with mercury ( silver ) or alcohol ( red ).


5. Mercury will expand when heated.

6. The volume of mercury increases as the mercury expands.

7. This will cause the mercury level in the tube to rise.

8. Mercury will contract when cooled.

9. The volume of mercury decreases as the mercury contracts.

10.This will cause the mercury level in the tube to fall.

11.The rise and fall of mercury level shows the temperature reading of an object.