## Measurement of Temperature – Class 11 | Chapter – 11 | Physics Short Notes Series PDF for NEET & JEE

Measurement of Temperature: Temperature is typically measured using a thermometer, which is an instrument that detects and measures changes in temperature. There are several types of thermometers, including:

• Mercury thermometer: This type of thermometer consists of a glass tube containing mercury, which expands and contracts as the temperature changes. The scale on the thermometer is marked with degrees Celsius or Fahrenheit.
• Digital thermometer: This type of thermometer uses a digital display to show the temperature. It may use a thermistor or other electronic component to measure temperature.
• Infrared thermometer: This type of thermometer measures temperature without making physical contact with the object being measured. It works by detecting the infrared radiation emitted by the object.
• Bimetallic thermometer: This type of thermometer consists of two strips of metal with different coefficients of thermal expansion that are bonded together. As the temperature changes, the strips bend, and the movement is displayed on a scale.

No matter what type of thermometer is used, it is important to follow the manufacturer’s instructions for proper usage and calibration. The accuracy of the thermometer can also be affected by factors such as the environment in which it is used and how it is stored.

## Temperature Measuring Devices

There are several devices that can be used to measure temperature, including:

• Thermometer: A thermometer is a device that measures temperature by using a thermometric material such as mercury, alcohol, or a thermocouple. Thermometers can be digital or analog and come in various sizes and shapes.
• Infrared thermometer: An infrared thermometer measures temperature without making physical contact with the object being measured. It works by detecting the infrared radiation emitted by the object. Infrared thermometers are often used to measure the temperature of surfaces that are difficult to access or in situations where physical contact may damage the object.
• Thermocouple: A thermocouple is a device that consists of two dissimilar metals joined together. When the junction of the metals is heated or cooled, a voltage is produced that is proportional to the temperature difference. Thermocouples are often used in industrial settings to measure high temperatures.
• RTD (Resistance Temperature Detector): An RTD is a device that measures temperature by measuring changes in electrical resistance. RTDs are often made of platinum or nickel and are highly accurate and stable over a wide temperature range.
• Thermistor: A thermistor is a type of resistor that changes its resistance with changes in temperature. Thermistors are often used in electronic devices because of their small size and sensitivity to temperature changes.
• Data logger: A data logger is a device that records temperature readings over time. Data loggers can be used to monitor temperature in a variety of settings, including refrigerators, freezers, and shipping containers.

Each of these devices has its own strengths and weaknesses, and the choice of device will depend on the specific application and requirements.

## Applications of Measurement of Temperature

The measurement of temperature has many applications across various fields, including:

• Medical: Measurement of temperature is used in medical applications to monitor body temperature, diagnose fever, and track the effectiveness of treatments. This includes measuring the temperature of the body, ambient temperature, and the temperature of fluids used in medical procedures.
• Food industry: Measurement of temperature is critical in the food industry to ensure food safety and prevent spoilage. Temperature measurement is used to monitor cooking, cooling, and storage temperatures of food products.
• HVAC:Measurement of temperature is used in heating, ventilation, and air conditioning (HVAC) systems to control temperature and maintain comfortable indoor environments.
• Industrial processes: Measurement of temperature is used in various industrial processes to monitor temperature, control heating or cooling, and maintain consistent process conditions. This includes applications in manufacturing, chemical processing, and power generation.
• Environmental monitoring: Measurement of temperature is used in environmental monitoring applications to monitor air and water temperature, track climate change, and predict weather patterns.
• Automotive: Measurement of temperature is used in automotive applications to monitor engine temperature, transmission temperature, and other critical components.
• Electronics: Measurement of temperature is used in electronics to monitor the temperature of electronic components and prevent overheating and damage.
• Research: Measurement of temperature is essential in research applications, including material science, physics, chemistry, and biology, where precise temperature control and measurement are required.

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