TEMPERATURE AND HEAT

MEASUREMENT OF TEMPERATURE


Before learning how to measure temperature, let us learn what is temperature

Temperature is a relative measure, or indication of hotness or coldness. A hot utensil is said to have a high temperature, and ice cube to have a low temperature.


















A measure of temperature is obtained using a thermometer. ( A thermometer is a device that measures temperature using a variety of different principles)

1. About Digital Thermometers

2. Appliance Thermometers

3. Bimetallic-Coil Thermometers

4. Calibrating the Thermometers

5. Cooking Temperatures

6. Disposable Thermometers

7. Food Safety Temperature Guide

8. Instant-Read Bimetallic Coil Thermometers

9. Oven Cord Thermometers

10. Oven Safe Bimetallic Coil Thermometers

11. Oven Thermometers

12 Placing the Thermometer

13. Refrigerator and Freezer Thermometers

14. Thermistor Thermometers

15. Thermocouple Thermometers

16. Thermometer Fork

Many physical properties of materials change sufficiently with temperature to be used as the basis for constructing thermometers. The commonly used property is variation of the volume of a liquid with temperature. For example, a common thermometer (the liquid-in-glass type) with
which you are familiar. Mercury and alcohol are the liquids used in most liquid-in-glass
thermometers. Thermometers are calibrated so that a numerical value may be assigned to a given temperature.

For the definition of any standard scale, two fixed reference points are needed. Since all substances change dimensions with temperature, an absolute reference for expansion is not available. However, the necessary fixed points may be correlated to physical phenomena that always occur at the same temperature. The ice point and the steam point of water are two convenient fixed points and are known as the freezing and boiling points. These two points are the temperatures at which pure water freezes and boils under standard pressure. The two familiar temperature scales are the Fahrenheit temperature scale and the Celsius temperature scale. The ice and steam point have values 32 °F and 212 °F respectively, on the Fahrenheit scale and 0 °C and 100 °C on the Celsius scale. On the Fahrenheit scale, there are 180 equal intervals between two reference points, and on the celsius scale, there are 100.


'scale of temperature' A reference scale with respect to which the temperatures can be measured is known as 'scale of temperature'. Various scales of temperatures are in use. Important scales of temperature are:

• Celsius scale

• Fahrenheit scale

• Kelvin Scale

Lower and upper fixed point of temperature

To devise a scale of temperature, fixed reference points (temperature) are required, with respect to which all other temperatures are measured. For both Celsius and Fahrenheit Scales of temperatures, the fixed points are as follows:

Lower fixed point:

Melting point of pure ice at normal atmospheric pressure is regarded as the lower fixed point