Fundamental Concepts of Physics: Thermodynamics & Waves

Fundamental Concepts in Physics

The Atom

An atom is composed of electrons, protons, and neutrons.

Temperature

Temperature is the physical quantity that describes the sensation of cold or hot, directly related to the average kinetic energy of molecules. It represents the average kinetic energy of each molecule.

Heat

Heat is the transfer of energy from one body to another due to a temperature difference. It is a form of energy that can be perceived through temperature variations.

Types of Thermal Expansion

• Linear Expansion
• Surface Expansion
• Volumetric Expansion

Thermodynamics

Thermodynamics is the branch of physics that studies heat transfer and the conversion of energy into its various forms.

Laws of Thermodynamics

• Zeroth Law
• First Law
• Second Law

Zeroth Law of Thermodynamics

If two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed from one form to another. In a closed system, the total amount of energy remains constant.

Second Law of Thermodynamics

It is impossible to build a heat engine that continuously transforms all the heat it receives into work without any other effect.

Entropy

Entropy is a measure of disorder or randomness in a system. It describes the number of different microscopic arrangements that a system can have while appearing the same macroscopically.

What is a Wave?

A wave is a disturbance that propagates regularly in space and time, transmitting energy progressively from one region to another without the net transfer of matter.

Types of Waves

• Transverse Waves: When the medium through which a wave propagates vibrates perpendicular to the direction of wave propagation.
• Longitudinal Waves: When particles of the medium vibrate parallel to the direction of wave propagation.

Key Characteristics of Waves

• Equilibrium Line (ab): The undisturbed position of the medium.
• Crest: The highest point of a wave.
• Trough (Valley): The lowest point of a wave.
• Node: Points on a wave that remain at the equilibrium position at all times.
• Elongation: The displacement of any point on the wave from its equilibrium position.
• Amplitude: The maximum displacement of a point on a wave from its equilibrium position.
• Wavelength (λ): The distance between two consecutive crests or troughs (valleys). It is expressed in units of length (e.g., meters, centimeters, kilometers) and is represented by the Greek letter lambda (λ).
• Period (T): The time it takes for a wave point to complete one full oscillation or cycle. (Often expressed as T = Total Time / Number of Oscillations).
• Frequency (f): The number of oscillations a wave completes in one unit of time. The unit of frequency is Hertz (Hz). (f = 1/T).