Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Heat is a form of energy that flows from a body at a higher temperature to a body at a lower temperature. Its S.I. unit is the Joule ().
Temperature is the reliable measure of the hotness or coldness of an object. It is measured using a device called a thermometer.
The Clinical Thermometer is used to measure human body temperature. It has a range from to . It contains a 'kink' (constriction) near the bulb to prevent the mercury level from falling on its own.
The Laboratory Thermometer is used for measuring temperatures in science labs. Its range is generally from to . It does not have a kink, so readings must be taken while the thermometer is in contact with the substance.
The normal temperature of the human body is ().
Digital thermometers are preferred nowadays as they do not contain toxic Mercury ().
Transfer of heat occurs through three modes: Conduction (solids), Convection (liquids/gases), and Radiation (vacuum/no medium required).
📐Formulae
💡Examples
Problem 1:
A person has a high fever and their body temperature is recorded as . What is this temperature in Celsius ()?
Solution:
Using the formula , substitute :
Explanation:
To convert Fahrenheit to Celsius, we subtract from the Fahrenheit value and then multiply by the fraction .
Problem 2:
Why is a Laboratory Thermometer not suitable for measuring human body temperature?
Solution:
A Laboratory Thermometer does not have a 'kink'. If used on a human, the mercury level would drop immediately upon removing it from the mouth, making it impossible to get an accurate reading. Also, its scale is usually too large ( to ) for the small range of human body temperature.
Explanation:
The 'kink' in a clinical thermometer is essential because it breaks the mercury thread, preventing it from falling back into the bulb until the thermometer is jerked.