How are temperature and heat related?
Temperature is a measure of degree of hotness of a body. Heat refers to the amount of thermal energy that is being transferred from a hotter to a colder region.
How do we measure temperature?
Our hands are able to tell us how hot or cold an object is by touch. However, we know from experience that our sense of touch is a poor estimate of temperature. As with any other physical quantity, we have to give a numerical value to temperature before we can measure it. Any instrument which is used to measure temperature can be called a thermometer and we need to invent a scale for the thermometer.
We need an instrument, the thermometer, to measure temperature accurately. The thermometer makes use of certain substances, such as mercury, to measure temperature. Thrse substances have physical properties that vary continuously with temperature, and are called thermometric sunstances. There are several types of thermometers. The choice of what to use will depend on the range of temperatures to be measured, the accuracy required and the physical conditions of the matter concerned. Exampel of physical properties used for designing thermometers are:
1. the expansion of a column of a liquid in a capillary tube
2. the electrical resistance of a plantinum wire
3. the voltage of a thermocouple
4. the expansion of a bimetallic strip
5. the pressure of a gas at constant rate
So what makes a good thermometer?
1. An easy to read scale
2. Safe to use
3. Responsive to temperature changes
4. Sensitive to small temperature changes
5. Able to measure a wide range of temperatures
Temperature is a measure of degree of hotness of a body. Heat refers to the amount of thermal energy that is being transferred from a hotter to a colder region.
How do we measure temperature?
Our hands are able to tell us how hot or cold an object is by touch. However, we know from experience that our sense of touch is a poor estimate of temperature. As with any other physical quantity, we have to give a numerical value to temperature before we can measure it. Any instrument which is used to measure temperature can be called a thermometer and we need to invent a scale for the thermometer.
We need an instrument, the thermometer, to measure temperature accurately. The thermometer makes use of certain substances, such as mercury, to measure temperature. Thrse substances have physical properties that vary continuously with temperature, and are called thermometric sunstances. There are several types of thermometers. The choice of what to use will depend on the range of temperatures to be measured, the accuracy required and the physical conditions of the matter concerned. Exampel of physical properties used for designing thermometers are:
1. the expansion of a column of a liquid in a capillary tube
2. the electrical resistance of a plantinum wire
3. the voltage of a thermocouple
4. the expansion of a bimetallic strip
5. the pressure of a gas at constant rate
So what makes a good thermometer?
1. An easy to read scale
2. Safe to use
3. Responsive to temperature changes
4. Sensitive to small temperature changes
5. Able to measure a wide range of temperatures
