Understanding Thermometers: Their Types, Uses, And Importance

Thermometers are instruments used to measure and indicate temperature. There are multiple types of thermometers in the contemporary market. Different types are used for different reasons, for example, research, cooking, and monitoring the body temperature of patients.

Have you ever wondered how we accurately measure temperature? From the mundane to the critical, thermometers play an essential role in our daily lives and various industries. Whether you're cooking a perfect meal, checking a fever, or conducting laboratory experiments, understanding the different types of thermometers is vital.

The world of thermometers is diverse, with options suited to specific tasks. Each type has its unique features and applications, making it crucial to select the right one for your needs. In this article, we will explore the various types of thermometers available today, their functions, and the pros and cons associated with each to help you make informed decisions.

Types of Thermometers Available Today

Many, if not all, of us have used thermometers for various reasons. Most people know those used to monitor patients' temperatures and those found in school science labs. Thermometers can be classified into various categories based on their usage, principles, and design.

Different applications demand different types of thermometers. For example, a cooking thermometer differs significantly from a clinical thermometer used to monitor body temperatures. Understanding these differences can enhance your ability to choose the right thermometer for any situation.

What is a Thermometer?

A thermometer is a device used to detect the temperature or temperature difference (the degree of hotness or coldness) of a person or object. The two primary components of this device are a temperature sensor and a mechanism for converting what it senses into a numerical value.

In essence, thermometers provide a crucial function in various fields, from healthcare to cooking and industrial applications. Below is an exploration of the different types of thermometers and their uses.

Classification Based on Working Principle

Thermometers are classified into two categories based on their working principles:

• Empirical Thermometers: These rely on the relationship between pressure, volume, and temperature of the thermometric material, such as mercury, which expands when heated.
• Absolute Thermometers: These measure temperature based on the theoretical concept of absolute zero, which is the lowest possible temperature.

Note: Empirical thermometers may not always agree with absolute thermometers on their numerical scale readings.

Classification Based on Function

Thermometers also come in various sizes and shapes, depending on the needs of the user. They can be classified into two broad categories based on function:

• Clinical Thermometers: Also known as medical thermometers, these are designed for clinical use and determine body temperature.
• Laboratory Thermometers: These are used to monitor temperatures other than body temperatures. Lab thermometers are commonly used to measure boiling points, freezing points, and the temperatures of different objects in labs and testing.

Different Types of Clinical Thermometers

There are multiple types of medical thermometers in the world. Let us look at the different types and their uses.

Regular Digital Thermometer

A regular digital thermometer uses a heat sensor. It has a smart electronic circuit and a display screen for showing measurements. It can be used to take readings from under the tongue or armpit. This device is considered to be the most accurate of all types of clinical thermometers.

Advantages:

• Inexpensive
• Easy to use
• Accurate
• Easy to maintain

Disadvantages:

• Prone to damage if dropped
• Battery power runs out often

Mercury Thermometer

A mercury thermometer has a glass tube filled with mercury. A standard temperature scale is marked on the tube. With temperature changes, the mercury expands and contracts, allowing temperature readings from the scale. This device can be used in homes, schools, and industries to determine body, liquid, and vapor temperatures.

Advantages:

• Measures even high temperatures
• Fast response time
• More durable than alcohol thermometers

Disadvantages:

• If the bulb cracks and mercury spills, it can be dangerous.
• Unable to detect frigid temperatures.

Plastic Strip Thermometer / Forehead Thermometer Strips

This device is the least invasive way to take a child's temperature. You hold the strip on the forehead until the color registers. Note that it may not produce precise temperature readings.

Advantages:

• Non-invasive
• Cheap
• Easy to use

Disadvantage:

• Often inaccurate

Pacifier Thermometer

This thermometer looks like a pacifier and is primarily used to take the body temperature of babies who are at least three months old. To use it, give it to a baby and wait for the reading. The child should be calm for an accurate reading.

Advantages:

• Easy to use
• Relatively affordable

Disadvantages:

• More than three minutes needed to reach a steady state.
• Often inaccurate if the baby is not calm.

Forehead / Temporal Thermometer

Forehead thermometers gained popularity during the COVID-19 pandemic. They use infrared technology to read heat and are preferred because they are a quick and sterile way to assess temperature.

Advantages:

• Non-intrusive
• Easy to use
• Fast response
• Does not require body contact

Disadvantages:

• Requires close proximity during measurement.
• Accuracy varies between models.

Different Types of Laboratory Thermometers

Lab thermometers typically have a temperature range of -10 to 110°C and are used in industries and science labs to measure boiling and freezing points. Below are types of thermometers used in physics, chemistry, biology, and industrial labs.

Liquid-in-Glass Thermometer

A liquid-in-glass thermometer is made with a sealed glass containing a liquid, usually mercury or red alcohol. The volume of the liquid fluctuates as the temperature rises or falls. As the temperature rises, the liquid expands and rises in response. It is commonly used in high school labs.

Advantages:

• Inexpensive
• Easy to use

Disadvantages:

• Fragile and prone to breakage
• Cannot be read from a distance

Pyrometer

A pyrometer is a remote-sensing thermometer used to measure the temperature of distant objects. The temperature is determined by the thermal radiation emitted by the object.

Advantages:

• Non-contact and non-intrusive
• Measures extremely high temperatures

Disadvantages:

• Expensive
• Less sensitive at low temperatures

Bimetallic Strip Thermometer

The bimetallic strip is a durable thermometer made of two strips of different metals. When heated, the metallic strips expand at different rates, resulting in a bending effect that is used to measure temperature change.

Advantages:

• Suitable for wide temperature ranges
•