Temperature and Thermometers
Temperature and Thermometers
The Temperature of an object is a measure of the hotness or coldness of that object.
An alternative way to think of temperature is to say that “the temperature of an object is a number – on some manmade scale – that indicates the hotness of the object”.
‘Hotness’ in turn is a measure of the kinetic energy of the molecules of the material.
Note: You must use the term ‘hotness’.*
The SI unit of temperature is the Kelvin (K)*
Relationship between degrees Celsius and Kelvin*:
Thermometric Properties
A Thermometric Property is any physical property that changes measurably with temperature.
Note: You must use the term ‘measurably’.
Examples of thermometric properties:
• Length of a column of liquid, e.g. mercury and alcohol thermometers,
• Electrical resistance (see chapter 23),
• Colour (colour ‘strips’ are sometimes used by nurses and placed against a person’s forehead),
• Emf of a thermocouple (emf is a fancy word word for ‘voltage’),
• Volume of gas at constant pressure,
• Pressure of a gas at constant volume.
Disagreement between thermometers
Two different types of thermometer will give slightly different readings at the same temperature.*
This means we need to agree on one particular thermometer to have as a standard.
Practical Thermometers
• Clinical thermometer
• Oven thermometer
• Temperature gauge in a car
Clinical thermometer; Two Main Features:
Short range because temperature of the human body doesn’t vary much either side of normal body temperature (37.60 C).
A kink to prevent the liquid falling back down when the thermometer is removed from the mouth and held vertically.
Experiment: Using a thermometric property to measure temperature*
1. Note the value of the thermometric property in melting ice (00 C) and also in boiling water (1000 C).
2. Plot these two points on a graph and draw a straight line joining them.
3. For an unknown temperature, note the thermometric property and use
The Temperature of an object is a measure of the hotness or coldness of that object.
An alternative way to think of temperature is to say that “the temperature of an object is a number – on some manmade scale – that indicates the hotness of the object”.
‘Hotness’ in turn is a measure of the kinetic energy of the molecules of the material.
Note: You must use the term ‘hotness’.*
The SI unit of temperature is the Kelvin (K)*
Relationship between degrees Celsius and Kelvin*:
Thermometric Properties
A Thermometric Property is any physical property that changes measurably with temperature.
Note: You must use the term ‘measurably’.
Examples of thermometric properties:
• Length of a column of liquid, e.g. mercury and alcohol thermometers,
• Electrical resistance (see chapter 23),
• Colour (colour ‘strips’ are sometimes used by nurses and placed against a person’s forehead),
• Emf of a thermocouple (emf is a fancy word word for ‘voltage’),
• Volume of gas at constant pressure,
• Pressure of a gas at constant volume.
Disagreement between thermometers
Two different types of thermometer will give slightly different readings at the same temperature.*
This means we need to agree on one particular thermometer to have as a standard.
Practical Thermometers
• Clinical thermometer
• Oven thermometer
• Temperature gauge in a car
Clinical thermometer; Two Main Features:
Short range because temperature of the human body doesn’t vary much either side of normal body temperature (37.60 C).
A kink to prevent the liquid falling back down when the thermometer is removed from the mouth and held vertically.
Experiment: Using a thermometric property to measure temperature*
1. Note the value of the thermometric property in melting ice (00 C) and also in boiling water (1000 C).
2. Plot these two points on a graph and draw a straight line joining them.
3. For an unknown temperature, note the thermometric property and use