Thermometers

Thermometers are used to measure temperature.

The temperature of a material tells us how hot or cold it is.

The units for temperature are Degrees Celsius ( °C ).

Material Temperature ( °C )

Air in room

Air outsideSkinIce

Water (kettle)

Liquid-in-Glass Thermometers

All thermometers must have some property that changes when the temperature changes.

In a liquid-in-glass thermometer the volume of the liquid changes when the temperature changes.

When the temperature increases the liquid expands (larger volume).

When the temperature decreases the liquid contracts (smaller volume).

The Clinical Thermometer

The clinical thermometer is a special liquid-in-glass thermometer used by doctors and nurses.

It works in the same way as an ordinary liquid-in-glass thermometer but with some additional features.

35 42

1. A kink in the tube stops the temperature reading falling when the clinical thermometer is removed from the patient.

2. The scale is shorter and more accurate ( measures to 0.1 °C )

3. Its triangular shape magnifies the liquid making it easier to read.

http://upload.wikimedia.org/wikipedia/commons/9/93/Clinical_thermometer_38.7.JPG

Using the Clinical Thermometer

1. Shake the thermometer to get liquid below the kink.

2. Place under tongue or armpit of patient.

3. Wait for a few minutes.

4. Remove from patient and read temperature.

Body Temperature & Illness

Normal internal body temperature is 37 °C.

A body temperature a few degrees above 37 °C can mean a patient is ill.

Hyperthermia is when the body temperature increases way above normal.

Death occurs at about 45 °C.

Hypothermia is when the body temperature falls way below normal.

Death occurs at about 26 °C.