Why in the News?
An article in The Hindu explained the scientific principles behind thermometers, temperature scales, absolute zero, and ultra-cold atomic physics, highlighting how measurement of temperature evolved from mercury thermometers to quantum physics-based studies of cold atoms.
What is Temperature?
- Temperature is a measure of the average kinetic energy of atoms and molecules in a substance.
- When heat is supplied:
- Atoms and molecules move faster.
- When heat is removed:
- Their motion slows down.
- Thus, temperature reflects the degree of atomic agitation inside matter.
Celsius Scale
- Developed by: Anders Celsius
Basis of the Scale
- 0°C: Freezing point of water
- 100°C: Boiling point of water
- The interval between these two points is divided into 100 equal parts.
Mercury Thermometers
Why Mercury is Used
- Uniform expansion on heating
- Easily visible liquid metal
- Good thermal conductor
Digital Thermometers
- Modern digital thermometers use Semiconductor materials
- Principle
- Semiconductors conduct limited electricity.
- Higher temperature releases more free electrons.
- Increased electric current is measured electronically and converted into temperature readings.
[2021] In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?
1. Area of the hole in the lid
2. Temperature of the flame
3. Weight of the lid
Select the correct answer using the code given below.
[A] 1 and 2 only
[B] 2 and 3 only
[C] 1 and 3 only
[D] 1, 2 and 3
