You may need to check an oral temperature to learn if you or a family member has a fever. "Fever" is a word used for a temperature that is higher than normal for the body. Fever is usually a sign of illness, infection, or other conditions. The normal oral temperature for adults is about ° F (37° C). The normal oral temperature for a child is between ° and ° F (° and ° C). The normal oral temperature for older persons is ° F (36° C). Body temperature changes slightly through the day and night, and may change based on your activity.
RTDs are wire windings or other thin film serpentines that exhibit changes in resistance with changes in measure temperature using the positive temperature coefficient of electrical resistance of metals. The hotter they become, the higher the value of their electrical resistance. Platinum is the most commonly used material because it is nearly linear over a wide range of temperatures, is very accurate, and has a fast response time. RTDs can also be made of copper or nickel. o Advantages of RTDs include their stable output for long periods of time. They are also easy to calibrate and provide very accurate readings. o Disadvantages include a smaller overall temperature range, higher initial cost, and a less rugged design
Fevers are reflective of an increase in your body temperature. Mild fevers are often beneficial because they represent the body trying to defend itself against infections. Many disease-causing (pathogenic) microorganisms thrive in a narrow temperature range, so a mild fever prevents them from reproducing.  However, some fevers may be related to connective tissue disease or malignancies. High fevers (103 °F or °C or greater for an adult) are potentially dangerous and should be closely monitored with a thermometer. There are many types and models of thermometers meant for different areas of the body. The most appropriate choice is typically determined by the age of the person with the fever — some thermometers are better for small children, for example. Once you've chosen the most appropriate thermometer, using it is relatively straightforward.